diff --git a/src/fs.rs b/src/fs.rs
index 76b31c307e2b424921d913e96b6d5f5d725294a6..674649b544b4ef3e6c6582a022a966fa63f3e7e1 100644
--- a/src/fs.rs
+++ b/src/fs.rs
@@ -62,7 +62,7 @@ impl File {
 
 impl io::Read for &File {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        match Sys::read(self.fd, buf).or_minus_one_errno() /* TODO */ {
+        match Sys::read(self.fd, buf).map(|read| read as ssize_t).or_minus_one_errno() /* TODO */ {
             -1 => Err(io::last_os_error()),
             ok => Ok(ok as usize),
         }
@@ -71,7 +71,10 @@ impl io::Read for &File {
 
 impl io::Write for &File {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        match Sys::write(self.fd, buf).or_minus_one_errno() {
+        match Sys::write(self.fd, buf)
+            .map(|read| read as ssize_t)
+            .or_minus_one_errno()
+        {
             -1 => Err(io::last_os_error()),
             ok => Ok(ok as usize),
         }
diff --git a/src/header/fcntl/mod.rs b/src/header/fcntl/mod.rs
index 6774e6b49e344288635ffc9f1972dba3fb8c260e..c21b279287a3f0235e005341d9f1cf382d20e0c2 100644
--- a/src/header/fcntl/mod.rs
+++ b/src/header/fcntl/mod.rs
@@ -55,7 +55,7 @@ pub unsafe extern "C" fn fcntl(fildes: c_int, cmd: c_int, mut __valist: ...) ->
         _ => 0,
     };
 
-    Sys::fcntl(fildes, cmd, arg)
+    Sys::fcntl(fildes, cmd, arg).or_minus_one_errno()
 }
 
 #[no_mangle]
diff --git a/src/header/poll/mod.rs b/src/header/poll/mod.rs
index cbf4e9defbc2238964292966d07f28cb83720ed8..cd9979d6cbf88e46d852bc4384e94391117372da 100644
--- a/src/header/poll/mod.rs
+++ b/src/header/poll/mod.rs
@@ -3,6 +3,7 @@
 use core::{mem, slice};
 
 use crate::{
+    error::ResultExt,
     fs::File,
     header::sys_epoll::{
         epoll_create1, epoll_ctl, epoll_data, epoll_event, epoll_wait, EPOLLERR, EPOLLHUP, EPOLLIN,
@@ -77,13 +78,13 @@ pub fn poll_epoll(fds: &mut [pollfd], timeout: c_int) -> c_int {
 
         pfd.revents = 0;
 
-        if epoll_ctl(*ep, EPOLL_CTL_ADD, pfd.fd, &mut event) < 0 {
+        if unsafe { epoll_ctl(*ep, EPOLL_CTL_ADD, pfd.fd, &mut event) } < 0 {
             return -1;
         }
     }
 
     let mut events: [epoll_event; 32] = unsafe { mem::zeroed() };
-    let res = epoll_wait(*ep, events.as_mut_ptr(), events.len() as c_int, timeout);
+    let res = unsafe { epoll_wait(*ep, events.as_mut_ptr(), events.len() as c_int, timeout) };
     if res < 0 {
         return -1;
     }
diff --git a/src/header/pty/redox.rs b/src/header/pty/redox.rs
index f22dfc43edaca9b00088482283aef0b0142fd844..f99f882a0fda0a39225cf12c2e60d1c3ac2aebba 100644
--- a/src/header/pty/redox.rs
+++ b/src/header/pty/redox.rs
@@ -12,7 +12,9 @@ pub(super) unsafe fn openpty(name: &mut [u8]) -> Result<(c_int, c_int), ()> {
     }
 
     // TODO: better error handling
-    let count = Sys::fpath(master, name).or_minus_one_errno();
+    let count = Sys::fpath(master, name)
+        .map(|u| u as ssize_t)
+        .or_minus_one_errno();
     if count < 0 {
         unistd::close(master);
         return Err(());
diff --git a/src/header/signal/mod.rs b/src/header/signal/mod.rs
index 61e1780f5b32afc2279c17302fa0d044c6239853..1457a7337d156064da974136b9bb8e5da9314449 100644
--- a/src/header/signal/mod.rs
+++ b/src/header/signal/mod.rs
@@ -88,7 +88,7 @@ pub type stack_t = sigaltstack;
 
 #[no_mangle]
 pub extern "C" fn kill(pid: pid_t, sig: c_int) -> c_int {
-    Sys::kill(pid, sig)
+    Sys::kill(pid, sig).map(|()| 0).or_minus_one_errno()
 }
 #[no_mangle]
 pub extern "C" fn sigqueue(pid: pid_t, sig: c_int, val: sigval) -> c_int {
@@ -99,7 +99,7 @@ pub extern "C" fn sigqueue(pid: pid_t, sig: c_int, val: sigval) -> c_int {
 
 #[no_mangle]
 pub extern "C" fn killpg(pgrp: pid_t, sig: c_int) -> c_int {
-    Sys::killpg(pgrp, sig)
+    Sys::killpg(pgrp, sig).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
diff --git a/src/header/stdio/mod.rs b/src/header/stdio/mod.rs
index e36a182db69fde296dfb3c048d1380ff5c9c000f..6719aed47a87610be9c95868f839a32e22b23bcf 100644
--- a/src/header/stdio/mod.rs
+++ b/src/header/stdio/mod.rs
@@ -837,7 +837,7 @@ pub unsafe extern "C" fn pclose(stream: *mut FILE) -> c_int {
     fclose(stream);
 
     let mut wstatus = 0;
-    if Sys::waitpid(pid, &mut wstatus, 0) < 0 {
+    if Sys::waitpid(pid, &mut wstatus, 0).or_minus_one_errno() == -1 {
         return -1;
     }
 
diff --git a/src/header/stdlib/mod.rs b/src/header/stdlib/mod.rs
index 47dd99e5eb3c8ba75925a3270441b841e33d8b8e..9a290a9ed33d87903c97094039c34e0a6449fa3c 100644
--- a/src/header/stdlib/mod.rs
+++ b/src/header/stdlib/mod.rs
@@ -986,7 +986,9 @@ pub unsafe extern "C" fn realpath(pathname: *const c_char, resolved: *mut c_char
 
         let len = out.len();
         // TODO: better error handling
-        let read = Sys::fpath(*file, &mut out[..len - 1]).or_minus_one_errno();
+        let read = Sys::fpath(*file, &mut out[..len - 1])
+            .map(|read| read as ssize_t)
+            .or_minus_one_errno();
         if read < 0 {
             return ptr::null_mut();
         }
@@ -1320,7 +1322,7 @@ pub unsafe extern "C" fn system(command: *const c_char) -> c_int {
         unreachable!();
     } else if child_pid > 0 {
         let mut wstatus = 0;
-        if Sys::waitpid(child_pid, &mut wstatus, 0) == !0 {
+        if Sys::waitpid(child_pid, &mut wstatus, 0).or_minus_one_errno() == -1 {
             return -1;
         }
 
diff --git a/src/header/sys_epoll/mod.rs b/src/header/sys_epoll/mod.rs
index 831d6dca03addf51b194c1134e721b9a289c783e..8089642ae16a7a1d61ec53d2b8753a100ad5b059 100644
--- a/src/header/sys_epoll/mod.rs
+++ b/src/header/sys_epoll/mod.rs
@@ -3,6 +3,7 @@
 use core::ptr;
 
 use crate::{
+    error::ResultExt,
     header::signal::sigset_t,
     platform::{types::*, PalEpoll, Sys},
 };
@@ -64,13 +65,24 @@ pub extern "C" fn epoll_create(_size: c_int) -> c_int {
 
 #[no_mangle]
 pub extern "C" fn epoll_create1(flags: c_int) -> c_int {
-    trace_expr!(Sys::epoll_create1(flags), "epoll_create1({:#x})", flags)
+    trace_expr!(
+        Sys::epoll_create1(flags).or_minus_one_errno(),
+        "epoll_create1({:#x})",
+        flags
+    )
 }
 
 #[no_mangle]
-pub extern "C" fn epoll_ctl(epfd: c_int, op: c_int, fd: c_int, event: *mut epoll_event) -> c_int {
+pub unsafe extern "C" fn epoll_ctl(
+    epfd: c_int,
+    op: c_int,
+    fd: c_int,
+    event: *mut epoll_event,
+) -> c_int {
     trace_expr!(
-        Sys::epoll_ctl(epfd, op, fd, event),
+        Sys::epoll_ctl(epfd, op, fd, event)
+            .map(|()| 0)
+            .or_minus_one_errno(),
         "epoll_ctl({}, {}, {}, {:p})",
         epfd,
         op,
@@ -80,7 +92,7 @@ pub extern "C" fn epoll_ctl(epfd: c_int, op: c_int, fd: c_int, event: *mut epoll
 }
 
 #[no_mangle]
-pub extern "C" fn epoll_wait(
+pub unsafe extern "C" fn epoll_wait(
     epfd: c_int,
     events: *mut epoll_event,
     maxevents: c_int,
@@ -90,7 +102,7 @@ pub extern "C" fn epoll_wait(
 }
 
 #[no_mangle]
-pub extern "C" fn epoll_pwait(
+pub unsafe extern "C" fn epoll_pwait(
     epfd: c_int,
     events: *mut epoll_event,
     maxevents: c_int,
@@ -98,7 +110,9 @@ pub extern "C" fn epoll_pwait(
     sigmask: *const sigset_t,
 ) -> c_int {
     trace_expr!(
-        Sys::epoll_pwait(epfd, events, maxevents, timeout, sigmask),
+        Sys::epoll_pwait(epfd, events, maxevents, timeout, sigmask)
+            .map(|e| e as c_int)
+            .or_minus_one_errno(),
         "epoll_pwait({}, {:p}, {}, {}, {:p})",
         epfd,
         events,
diff --git a/src/header/sys_file/mod.rs b/src/header/sys_file/mod.rs
index 7d8e6324035c00ac9bd3e1a6470c3bca2d35c392..15e0f81ec1e868c22816362ac1cca1877c026534 100644
--- a/src/header/sys_file/mod.rs
+++ b/src/header/sys_file/mod.rs
@@ -1,6 +1,9 @@
 //! sys/file.h implementation
 
-use crate::platform::{types::*, Pal, Sys};
+use crate::{
+    error::ResultExt,
+    platform::{types::*, Pal, Sys},
+};
 
 pub const LOCK_SH: usize = 1;
 pub const LOCK_EX: usize = 2;
@@ -13,5 +16,5 @@ pub const L_XTND: usize = 2;
 
 #[no_mangle]
 pub extern "C" fn flock(fd: c_int, operation: c_int) -> c_int {
-    Sys::flock(fd, operation)
+    Sys::flock(fd, operation).map(|()| 0).or_minus_one_errno()
 }
diff --git a/src/header/sys_ioctl/linux.rs b/src/header/sys_ioctl/linux.rs
index 949052dbaeaa1fcaff8f3502c0e27a421849e324..e6b95848e0e64bc0a9726f48110aafa4c240dc66 100644
--- a/src/header/sys_ioctl/linux.rs
+++ b/src/header/sys_ioctl/linux.rs
@@ -1,9 +1,12 @@
-use crate::platform::{types::*, Sys};
+use crate::{
+    error::ResultExt,
+    platform::{types::*, Sys},
+};
 
 #[no_mangle]
 pub unsafe extern "C" fn ioctl(fd: c_int, request: c_ulong, out: *mut c_void) -> c_int {
     // TODO: Somehow support varargs to syscall??
-    Sys::ioctl(fd, request, out)
+    Sys::ioctl(fd, request, out).or_minus_one_errno()
 }
 
 pub const TCGETS: c_ulong = 0x5401;
diff --git a/src/header/sys_mman/mod.rs b/src/header/sys_mman/mod.rs
index 29f639a7a44ce6ea02bf5ff501d31f1d6ae225d3..3133a74159a01a962c09de1c70d04b3513d00ee2 100644
--- a/src/header/sys_mman/mod.rs
+++ b/src/header/sys_mman/mod.rs
@@ -1,7 +1,8 @@
 use crate::{
     c_str::{CStr, CString},
+    error::{Errno, ResultExt},
     header::{fcntl, unistd},
-    platform::{types::*, Pal, Sys},
+    platform::{types::*, Pal, Sys, ERRNO},
 };
 
 pub use self::sys::*;
@@ -45,12 +46,12 @@ pub const POSIX_MADV_WONTNEED: c_int = 4;
 
 #[no_mangle]
 pub unsafe extern "C" fn mlock(addr: *const c_void, len: usize) -> c_int {
-    Sys::mlock(addr, len)
+    Sys::mlock(addr, len).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
-pub extern "C" fn mlockall(flags: c_int) -> c_int {
-    Sys::mlockall(flags)
+pub unsafe extern "C" fn mlockall(flags: c_int) -> c_int {
+    Sys::mlockall(flags).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
@@ -62,7 +63,13 @@ pub unsafe extern "C" fn mmap(
     fildes: c_int,
     off: off_t,
 ) -> *mut c_void {
-    Sys::mmap(addr, len, prot, flags, fildes, off)
+    match Sys::mmap(addr, len, prot, flags, fildes, off) {
+        Ok(ptr) => ptr,
+        Err(Errno(errno)) => {
+            ERRNO.set(errno);
+            MAP_FAILED
+        }
+    }
 }
 
 #[no_mangle]
@@ -74,37 +81,49 @@ unsafe extern "C" fn mremap(
     mut __valist: ...
 ) -> *mut c_void {
     let new_address = __valist.arg::<*mut c_void>();
-    Sys::mremap(old_address, old_size, new_size, flags, new_address)
+    match Sys::mremap(old_address, old_size, new_size, flags, new_address) {
+        Ok(ptr) => ptr,
+        Err(Errno(errno)) => {
+            ERRNO.set(errno);
+            MAP_FAILED
+        }
+    }
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn mprotect(addr: *mut c_void, len: size_t, prot: c_int) -> c_int {
     Sys::mprotect(addr, len, prot)
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn msync(addr: *mut c_void, len: size_t, flags: c_int) -> c_int {
     Sys::msync(addr, len, flags)
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn munlock(addr: *const c_void, len: usize) -> c_int {
-    Sys::munlock(addr, len)
+    Sys::munlock(addr, len).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
-pub extern "C" fn munlockall() -> c_int {
-    Sys::munlockall()
+pub unsafe extern "C" fn munlockall() -> c_int {
+    Sys::munlockall().map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn munmap(addr: *mut c_void, len: size_t) -> c_int {
-    Sys::munmap(addr, len)
+    Sys::munmap(addr, len).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn madvise(addr: *mut c_void, len: size_t, flags: c_int) -> c_int {
     Sys::madvise(addr, len, flags)
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
 
 #[cfg(target_os = "linux")]
diff --git a/src/header/sys_random/mod.rs b/src/header/sys_random/mod.rs
index 957f8c7753eb374471cf095f37b8956799180716..36dfc3b408a74ee40adeade48b8ade6a5ee30dc7 100644
--- a/src/header/sys_random/mod.rs
+++ b/src/header/sys_random/mod.rs
@@ -1,6 +1,9 @@
 use core::slice;
 
-use crate::platform::{types::*, Pal, Sys};
+use crate::{
+    error::ResultExt,
+    platform::{types::*, Pal, Sys},
+};
 
 pub const GRND_NONBLOCK: c_uint = 1;
 pub const GRND_RANDOM: c_uint = 2;
@@ -11,4 +14,6 @@ pub unsafe extern "C" fn getrandom(buf: *mut c_void, buflen: size_t, flags: c_ui
         slice::from_raw_parts_mut(buf as *mut u8, buflen as usize),
         flags,
     )
+    .map(|read| read as ssize_t)
+    .or_minus_one_errno()
 }
diff --git a/src/header/sys_resource/mod.rs b/src/header/sys_resource/mod.rs
index d8a44b968651f075ed4fb5c328e7fecc9a0326c6..4e54febacbfcc7caa314049ce9fa15f0e8373798 100644
--- a/src/header/sys_resource/mod.rs
+++ b/src/header/sys_resource/mod.rs
@@ -68,7 +68,7 @@ pub const PRIO_USER: c_int = 2;
 
 #[no_mangle]
 pub unsafe extern "C" fn getpriority(which: c_int, who: id_t) -> c_int {
-    let r = Sys::getpriority(which, who);
+    let r = Sys::getpriority(which, who).or_minus_one_errno();
     if r < 0 {
         return r;
     }
@@ -99,4 +99,6 @@ pub unsafe extern "C" fn setrlimit(resource: c_int, rlp: *const rlimit) -> c_int
 #[no_mangle]
 pub unsafe extern "C" fn getrusage(who: c_int, r_usage: *mut rusage) -> c_int {
     Sys::getrusage(who, &mut *r_usage)
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
diff --git a/src/header/sys_select/mod.rs b/src/header/sys_select/mod.rs
index 6208ab831e1fb212ef6e5d728ce0ff7a2acdda49..22a981d19642259d38d77bed7ea548e4e74c3301 100644
--- a/src/header/sys_select/mod.rs
+++ b/src/header/sys_select/mod.rs
@@ -80,7 +80,7 @@ pub fn select_epoll(
                 data: epoll_data { fd },
                 ..Default::default()
             };
-            if epoll_ctl(*ep, EPOLL_CTL_ADD, fd, &mut event) < 0 {
+            if unsafe { epoll_ctl(*ep, EPOLL_CTL_ADD, fd, &mut event) } < 0 {
                 if platform::ERRNO.get() == errno::EPERM {
                     not_epoll += 1;
                 } else {
@@ -121,12 +121,14 @@ pub fn select_epoll(
             None => -1,
         }
     };
-    let res = epoll_wait(
-        *ep,
-        events.as_mut_ptr(),
-        events.len() as c_int,
-        epoll_timeout,
-    );
+    let res = unsafe {
+        epoll_wait(
+            *ep,
+            events.as_mut_ptr(),
+            events.len() as c_int,
+            epoll_timeout,
+        )
+    };
     if res < 0 {
         return -1;
     }
diff --git a/src/header/sys_stat/mod.rs b/src/header/sys_stat/mod.rs
index 17dfe6bcd339630422fce1e2b4cb433a548dc69a..5b75c31a30733d1592b7d51ce2c20f5d74fb929e 100644
--- a/src/header/sys_stat/mod.rs
+++ b/src/header/sys_stat/mod.rs
@@ -77,18 +77,18 @@ pub extern "C" fn fchmod(fildes: c_int, mode: mode_t) -> c_int {
 }
 
 #[no_mangle]
-pub extern "C" fn fstat(fildes: c_int, buf: *mut stat) -> c_int {
-    Sys::fstat(fildes, buf)
+pub unsafe extern "C" fn fstat(fildes: c_int, buf: *mut stat) -> c_int {
+    Sys::fstat(fildes, buf).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
-pub extern "C" fn __fxstat(_ver: c_int, fildes: c_int, buf: *mut stat) -> c_int {
+pub unsafe extern "C" fn __fxstat(_ver: c_int, fildes: c_int, buf: *mut stat) -> c_int {
     fstat(fildes, buf)
 }
 
 #[no_mangle]
-pub extern "C" fn futimens(fd: c_int, times: *const timespec) -> c_int {
-    Sys::futimens(fd, times)
+pub unsafe extern "C" fn futimens(fd: c_int, times: *const timespec) -> c_int {
+    Sys::futimens(fd, times).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
@@ -100,7 +100,8 @@ pub unsafe extern "C" fn lstat(path: *const c_char, buf: *mut stat) -> c_int {
         return -1;
     }
 
-    let res = Sys::fstat(fd, buf);
+    // TODO: Rustify
+    let res = Sys::fstat(fd, buf).map(|()| 0).or_minus_one_errno();
 
     Sys::close(fd);
 
@@ -147,7 +148,8 @@ pub unsafe extern "C" fn stat(file: *const c_char, buf: *mut stat) -> c_int {
         return -1;
     }
 
-    let res = Sys::fstat(fd, buf);
+    // TODO: Rustify
+    let res = Sys::fstat(fd, buf).map(|()| 0).or_minus_one_errno();
 
     Sys::close(fd);
 
diff --git a/src/header/sys_statvfs/mod.rs b/src/header/sys_statvfs/mod.rs
index 6bfde24f0cd1c90487944ae24745be2386ba3a0c..306e0436bf60adc890bf5c20b00dcd8585b72393 100644
--- a/src/header/sys_statvfs/mod.rs
+++ b/src/header/sys_statvfs/mod.rs
@@ -27,8 +27,8 @@ pub struct statvfs {
 }
 
 #[no_mangle]
-pub extern "C" fn fstatvfs(fildes: c_int, buf: *mut statvfs) -> c_int {
-    Sys::fstatvfs(fildes, buf)
+pub unsafe extern "C" fn fstatvfs(fildes: c_int, buf: *mut statvfs) -> c_int {
+    Sys::fstatvfs(fildes, buf).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
@@ -40,7 +40,7 @@ pub unsafe extern "C" fn statvfs(file: *const c_char, buf: *mut statvfs) -> c_in
         return -1;
     }
 
-    let res = Sys::fstatvfs(fd, buf);
+    let res = Sys::fstatvfs(fd, buf).map(|()| 0).or_minus_one_errno();
 
     Sys::close(fd);
 
diff --git a/src/header/sys_time/mod.rs b/src/header/sys_time/mod.rs
index e9641493ecffab1d7b118d42a98a9f1c3222e205..af5e895d03499ae781f906e7f0c67b83d2f58420 100644
--- a/src/header/sys_time/mod.rs
+++ b/src/header/sys_time/mod.rs
@@ -2,6 +2,7 @@
 
 use crate::{
     c_str::CStr,
+    error::ResultExt,
     header::time::timespec,
     platform::{types::*, Pal, PalSignal, Sys},
 };
@@ -39,6 +40,8 @@ pub struct fd_set {
 #[no_mangle]
 pub unsafe extern "C" fn getitimer(which: c_int, value: *mut itimerval) -> c_int {
     Sys::getitimer(which, value)
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
 
 #[no_mangle]
@@ -48,11 +51,13 @@ pub unsafe extern "C" fn setitimer(
     ovalue: *mut itimerval,
 ) -> c_int {
     Sys::setitimer(which, value, ovalue)
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn gettimeofday(tp: *mut timeval, tzp: *mut timezone) -> c_int {
-    Sys::gettimeofday(tp, tzp)
+    Sys::gettimeofday(tp, tzp).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
@@ -77,4 +82,6 @@ pub unsafe extern "C" fn utimes(path: *const c_char, times: *const timeval) -> c
         .as_ptr()
     };
     Sys::utimens(path, times_spec)
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
diff --git a/src/header/sys_wait/mod.rs b/src/header/sys_wait/mod.rs
index 3628353977a5e398687e784402529b2657a55a90..e482bb3211e3f84e153b17d5bc47505c8000188b 100644
--- a/src/header/sys_wait/mod.rs
+++ b/src/header/sys_wait/mod.rs
@@ -1,6 +1,7 @@
 //! sys/wait.h implementation for Redox, following
 //! http://pubs.opengroup.org/onlinepubs/7908799/xsh/syswait.h.html
 
+use crate::error::ResultExt;
 //use header::sys_resource::rusage;
 use crate::platform::{types::*, Pal, Sys};
 
@@ -47,5 +48,5 @@ pub unsafe extern "C" fn wait(stat_loc: *mut c_int) -> pid_t {
 
 #[no_mangle]
 pub unsafe extern "C" fn waitpid(pid: pid_t, stat_loc: *mut c_int, options: c_int) -> pid_t {
-    Sys::waitpid(pid, stat_loc, options)
+    Sys::waitpid(pid, stat_loc, options).or_minus_one_errno()
 }
diff --git a/src/header/time/mod.rs b/src/header/time/mod.rs
index 0ea67045389cc9a6f20a1681f75aa326dfcedf88..3942ecb2069253206842766c8c188dfdc28b43f6 100644
--- a/src/header/time/mod.rs
+++ b/src/header/time/mod.rs
@@ -488,8 +488,8 @@ pub unsafe extern "C" fn mktime(timeptr: *mut tm) -> time_t {
 }
 
 #[no_mangle]
-pub extern "C" fn nanosleep(rqtp: *const timespec, rmtp: *mut timespec) -> c_int {
-    Sys::nanosleep(rqtp, rmtp)
+pub unsafe extern "C" fn nanosleep(rqtp: *const timespec, rmtp: *mut timespec) -> c_int {
+    Sys::nanosleep(rqtp, rmtp).map(|()| 0).or_minus_one_errno()
 }
 
 #[no_mangle]
diff --git a/src/header/unistd/brk.rs b/src/header/unistd/brk.rs
index 7efa5c2be349baa816208309960a148745258d10..47907758cf23ae9dd93a300afe341e1308de7b76 100644
--- a/src/header/unistd/brk.rs
+++ b/src/header/unistd/brk.rs
@@ -1,6 +1,7 @@
 use core::ptr;
 
 use crate::{
+    error::ResultExtPtrMut,
     header::errno::ENOMEM,
     platform::{self, types::*, Pal, Sys},
 };
@@ -9,7 +10,7 @@ static mut BRK: *mut c_void = ptr::null_mut();
 
 #[no_mangle]
 pub unsafe extern "C" fn brk(addr: *mut c_void) -> c_int {
-    BRK = Sys::brk(addr);
+    BRK = Sys::brk(addr).or_errno_null_mut();
 
     if BRK < addr {
         platform::ERRNO.set(ENOMEM);
@@ -22,7 +23,7 @@ pub unsafe extern "C" fn brk(addr: *mut c_void) -> c_int {
 #[no_mangle]
 pub unsafe extern "C" fn sbrk(incr: intptr_t) -> *mut c_void {
     if BRK.is_null() {
-        BRK = Sys::brk(ptr::null_mut());
+        BRK = Sys::brk(ptr::null_mut()).or_errno_null_mut();
     }
 
     let old_brk = BRK;
@@ -30,7 +31,7 @@ pub unsafe extern "C" fn sbrk(incr: intptr_t) -> *mut c_void {
     if incr != 0 {
         let addr = old_brk.offset(incr);
 
-        BRK = Sys::brk(addr);
+        BRK = Sys::brk(addr).or_errno_null_mut();
 
         if BRK < addr {
             platform::ERRNO.set(ENOMEM);
diff --git a/src/header/unistd/mod.rs b/src/header/unistd/mod.rs
index 03ef809cbbed04d34049495d7c1763c38533a963..df8f8c6fa612211b2f844a05c5ba4f4508b1f065 100644
--- a/src/header/unistd/mod.rs
+++ b/src/header/unistd/mod.rs
@@ -9,7 +9,7 @@ use core::{
 
 use crate::{
     c_str::CStr,
-    error::ResultExt,
+    error::{Errno, ResultExt},
     header::{
         crypt::{crypt_data, crypt_r},
         errno, fcntl, limits,
@@ -17,7 +17,7 @@ use crate::{
         sys_ioctl, sys_resource, sys_time, sys_utsname, termios,
         time::timespec,
     },
-    platform::{self, types::*, Pal, Sys},
+    platform::{self, types::*, Pal, Sys, ERRNO},
 };
 
 use alloc::collections::LinkedList;
@@ -163,7 +163,7 @@ pub extern "C" fn daemon(nochdir: c_int, noclose: c_int) -> c_int {
         }
     }
 
-    match fork() {
+    match unsafe { fork() } {
         0 => {}
         -1 => return -1,
         _ => _exit(0),
@@ -283,6 +283,8 @@ pub unsafe extern "C" fn execve(
 ) -> c_int {
     let path = CStr::from_ptr(path);
     Sys::execve(path, argv, envp)
+        .map(|()| unreachable!())
+        .or_minus_one_errno()
 }
 
 #[cfg(target_os = "linux")]
@@ -344,12 +346,12 @@ pub extern "C" fn fdatasync(fildes: c_int) -> c_int {
 }
 
 #[no_mangle]
-pub extern "C" fn fork() -> pid_t {
-    let fork_hooks = unsafe { init_fork_hooks() };
+pub unsafe extern "C" fn fork() -> pid_t {
+    let fork_hooks = init_fork_hooks();
     for prepare in &fork_hooks[0] {
         prepare();
     }
-    let pid = Sys::fork();
+    let pid = Sys::fork().or_minus_one_errno();
     if pid == 0 {
         for child in &fork_hooks[2] {
             child();
@@ -375,7 +377,7 @@ pub extern "C" fn ftruncate(fildes: c_int, length: off_t) -> c_int {
 }
 
 #[no_mangle]
-pub extern "C" fn getcwd(mut buf: *mut c_char, mut size: size_t) -> *mut c_char {
+pub unsafe extern "C" fn getcwd(mut buf: *mut c_char, mut size: size_t) -> *mut c_char {
     let alloc = buf.is_null();
     let mut stack_buf = [0; limits::PATH_MAX];
     if alloc {
@@ -383,10 +385,13 @@ pub extern "C" fn getcwd(mut buf: *mut c_char, mut size: size_t) -> *mut c_char
         size = stack_buf.len();
     }
 
-    let ret = Sys::getcwd(buf, size);
-    if ret.is_null() {
-        return ptr::null_mut();
-    }
+    let ret = match Sys::getcwd(buf, size) {
+        Ok(()) => buf,
+        Err(Errno(errno)) => {
+            ERRNO.set(errno);
+            return ptr::null_mut();
+        }
+    };
 
     if alloc {
         let len = stack_buf
@@ -442,7 +447,7 @@ pub extern "C" fn getgid() -> gid_t {
 
 #[no_mangle]
 pub unsafe extern "C" fn getgroups(size: c_int, list: *mut gid_t) -> c_int {
-    Sys::getgroups(size, list)
+    Sys::getgroups(size, list).or_minus_one_errno()
 }
 
 // #[no_mangle]
@@ -506,12 +511,12 @@ pub extern "C" fn getpagesize() -> c_int {
 
 #[no_mangle]
 pub extern "C" fn getpgid(pid: pid_t) -> pid_t {
-    Sys::getpgid(pid)
+    Sys::getpgid(pid).or_minus_one_errno()
 }
 
 #[no_mangle]
 pub extern "C" fn getpgrp() -> pid_t {
-    Sys::getpgid(Sys::getpid())
+    Sys::getpgid(Sys::getpid()).or_minus_one_errno()
 }
 
 #[no_mangle]
@@ -526,7 +531,7 @@ pub extern "C" fn getppid() -> pid_t {
 
 #[no_mangle]
 pub extern "C" fn getsid(pid: pid_t) -> pid_t {
-    Sys::getsid(pid)
+    Sys::getsid(pid).or_minus_one_errno()
 }
 
 #[no_mangle]
@@ -535,8 +540,8 @@ pub extern "C" fn getuid() -> uid_t {
 }
 
 #[no_mangle]
-pub extern "C" fn getwd(path_name: *mut c_char) -> *mut c_char {
-    getcwd(path_name, limits::PATH_MAX)
+pub unsafe extern "C" fn getwd(path_name: *mut c_char) -> *mut c_char {
+    unsafe { getcwd(path_name, limits::PATH_MAX) }
 }
 
 #[no_mangle]
@@ -642,6 +647,7 @@ pub unsafe extern "C" fn pread(
         slice::from_raw_parts_mut(buf.cast::<u8>(), nbyte),
         offset,
     )
+    .map(|read| read as ssize_t)
     .or_minus_one_errno()
 }
 
@@ -676,6 +682,7 @@ pub unsafe extern "C" fn pwrite(
         slice::from_raw_parts(buf.cast::<u8>(), nbyte),
         offset,
     )
+    .map(|read| read as ssize_t)
     .or_minus_one_errno()
 }
 
@@ -683,7 +690,9 @@ pub unsafe extern "C" fn pwrite(
 pub unsafe extern "C" fn read(fildes: c_int, buf: *const c_void, nbyte: size_t) -> ssize_t {
     let buf = unsafe { slice::from_raw_parts_mut(buf as *mut u8, nbyte as usize) };
     trace_expr!(
-        Sys::read(fildes, buf).or_minus_one_errno(),
+        Sys::read(fildes, buf)
+            .map(|read| read as ssize_t)
+            .or_minus_one_errno(),
         "read({}, {:p}, {})",
         fildes,
         buf,
@@ -699,7 +708,9 @@ pub unsafe extern "C" fn readlink(
 ) -> ssize_t {
     let path = CStr::from_ptr(path);
     let buf = slice::from_raw_parts_mut(buf as *mut u8, bufsize as usize);
-    Sys::readlink(path, buf).or_minus_one_errno()
+    Sys::readlink(path, buf)
+        .map(|read| read as ssize_t)
+        .or_minus_one_errno()
 }
 
 #[no_mangle]
@@ -775,7 +786,7 @@ pub extern "C" fn sleep(seconds: c_uint) -> c_uint {
         tv_nsec: 0,
     };
     let rmtp = ptr::null_mut();
-    Sys::nanosleep(&rqtp, rmtp);
+    unsafe { Sys::nanosleep(&rqtp, rmtp).map(|()| 0).or_minus_one_errno() };
     0
 }
 
@@ -857,7 +868,9 @@ pub extern "C" fn ttyname_r(fildes: c_int, name: *mut c_char, namesize: size_t)
         return errno::ERANGE;
     }
 
-    let len = Sys::fpath(fildes, &mut name[..namesize - 1]).or_minus_one_errno();
+    let len = Sys::fpath(fildes, &mut name[..namesize - 1])
+        .map(|read| read as ssize_t)
+        .or_minus_one_errno();
     if len < 0 {
         return -platform::ERRNO.get();
     }
@@ -902,7 +915,9 @@ pub extern "C" fn usleep(useconds: useconds_t) -> c_int {
         tv_nsec: ((useconds % 1_000_000) * 1000) as c_long,
     };
     let rmtp = ptr::null_mut();
-    Sys::nanosleep(&rqtp, rmtp)
+    unsafe { Sys::nanosleep(&rqtp, rmtp) }
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
 
 // #[no_mangle]
@@ -913,5 +928,7 @@ pub extern "C" fn vfork() -> pid_t {
 #[no_mangle]
 pub unsafe extern "C" fn write(fildes: c_int, buf: *const c_void, nbyte: size_t) -> ssize_t {
     let buf = slice::from_raw_parts(buf as *const u8, nbyte as usize);
-    Sys::write(fildes, buf).or_minus_one_errno()
+    Sys::write(fildes, buf)
+        .map(|bytes| bytes as ssize_t)
+        .or_minus_one_errno()
 }
diff --git a/src/header/utime/mod.rs b/src/header/utime/mod.rs
index 5098cec7f576586b33e1a1c1e22c8c9cc391deab..bb17488d23c1d73971f453251bc7769a595cd158 100644
--- a/src/header/utime/mod.rs
+++ b/src/header/utime/mod.rs
@@ -2,6 +2,7 @@
 
 use crate::{
     c_str::CStr,
+    error::ResultExt,
     header::time::timespec,
     platform::{types::*, Pal, Sys},
 };
@@ -27,4 +28,6 @@ pub unsafe extern "C" fn utime(filename: *const c_char, times: *const utimbuf) -
         },
     ];
     Sys::utimens(filename, times_spec.as_ptr())
+        .map(|()| 0)
+        .or_minus_one_errno()
 }
diff --git a/src/lib.rs b/src/lib.rs
index 8ab4e35145c794f252916c2f2c768e82034d4dd5..4ae044e0dc1544bcae2112cf207f86b11aee2907 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,5 @@
 #![no_std]
+#![allow(warnings)]
 #![allow(non_camel_case_types)]
 #![allow(non_upper_case_globals)]
 #![allow(unused_variables)]
diff --git a/src/platform/allocator/sys.rs b/src/platform/allocator/sys.rs
index a2e6543fc19ff5392a1848989eb61cfa4c96effa..8241907c1df708a8649c08ee572db5b4dd642e38 100644
--- a/src/platform/allocator/sys.rs
+++ b/src/platform/allocator/sys.rs
@@ -25,7 +25,7 @@ static LOCK: Mutex<()> = Mutex::new(());
 
 unsafe impl Allocator for System {
     fn alloc(&self, size: usize) -> (*mut u8, usize, u32) {
-        let addr = unsafe {
+        let Ok(addr) = (unsafe {
             Sys::mmap(
                 0 as *mut _,
                 size,
@@ -34,36 +34,33 @@ unsafe impl Allocator for System {
                 -1,
                 0,
             )
+        }) else {
+            return (ptr::null_mut(), 0, 0);
         };
-        if addr as *mut c_void == MAP_FAILED {
-            (ptr::null_mut(), 0, 0)
-        } else {
-            (addr as *mut u8, size, 0)
-        }
+        (addr as *mut u8, size, 0)
     }
 
     fn remap(&self, ptr: *mut u8, oldsize: usize, newsize: usize, can_move: bool) -> *mut u8 {
         let flags = if can_move { MREMAP_MAYMOVE } else { 0 };
-        let ptr = unsafe { Sys::mremap(ptr as *mut _, oldsize, newsize, flags, ptr::null_mut()) };
-        if ptr as *mut c_void == MAP_FAILED {
-            ptr::null_mut()
-        } else {
-            ptr as *mut u8
-        }
+        let Ok(ptr) =
+            (unsafe { Sys::mremap(ptr as *mut _, oldsize, newsize, flags, ptr::null_mut()) })
+        else {
+            return ptr::null_mut();
+        };
+        ptr as *mut u8
     }
 
     fn free_part(&self, ptr: *mut u8, oldsize: usize, newsize: usize) -> bool {
         unsafe {
-            let rc = Sys::mremap(ptr as *mut _, oldsize, newsize, 0, ptr::null_mut());
-            if rc as *mut c_void != MAP_FAILED {
+            if Sys::mremap(ptr as *mut _, oldsize, newsize, 0, ptr::null_mut()).is_ok() {
                 return true;
             }
-            Sys::munmap(ptr.offset(newsize as isize) as *mut _, oldsize - newsize) == 0
+            Sys::munmap(ptr.add(newsize) as *mut _, oldsize - newsize).is_ok()
         }
     }
 
     fn free(&self, ptr: *mut u8, size: usize) -> bool {
-        unsafe { Sys::munmap(ptr as *mut _, size) == 0 }
+        unsafe { Sys::munmap(ptr as *mut _, size).is_ok() }
     }
 
     fn can_release_part(&self, _flags: u32) -> bool {
diff --git a/src/platform/linux/epoll.rs b/src/platform/linux/epoll.rs
index b92dc08d6b2923262a9167fa3464fcfb47415e5b..17b60959ad2695623d4262f0b8b5d594c4987423 100644
--- a/src/platform/linux/epoll.rs
+++ b/src/platform/linux/epoll.rs
@@ -1,34 +1,38 @@
-use super::{
-    super::{types::*, PalEpoll},
-    e, Sys,
+use super::{e_raw, Sys};
+use crate::{
+    error::Result,
+    header::{signal::sigset_t, sys_epoll::epoll_event},
+    platform::{types::*, PalEpoll},
 };
-use crate::header::{signal::sigset_t, sys_epoll::epoll_event};
 
 impl PalEpoll for Sys {
-    fn epoll_create1(flags: c_int) -> c_int {
-        unsafe { e(syscall!(EPOLL_CREATE1, flags)) as c_int }
+    fn epoll_create1(flags: c_int) -> Result<c_int> {
+        Ok(unsafe { e_raw(syscall!(EPOLL_CREATE1, flags))? as c_int })
     }
 
-    fn epoll_ctl(epfd: c_int, op: c_int, fd: c_int, event: *mut epoll_event) -> c_int {
-        unsafe { e(syscall!(EPOLL_CTL, epfd, op, fd, event)) as c_int }
+    unsafe fn epoll_ctl(epfd: c_int, op: c_int, fd: c_int, event: *mut epoll_event) -> Result<()> {
+        unsafe {
+            e_raw(syscall!(EPOLL_CTL, epfd, op, fd, event))?;
+        }
+        Ok(())
     }
 
-    fn epoll_pwait(
+    unsafe fn epoll_pwait(
         epfd: c_int,
         events: *mut epoll_event,
         maxevents: c_int,
         timeout: c_int,
         sigmask: *const sigset_t,
-    ) -> c_int {
+    ) -> Result<usize> {
         unsafe {
-            e(syscall!(
+            e_raw(syscall!(
                 EPOLL_PWAIT,
                 epfd,
                 events,
                 maxevents,
                 timeout,
                 sigmask
-            )) as c_int
+            ))
         }
     }
 }
diff --git a/src/platform/linux/mod.rs b/src/platform/linux/mod.rs
index 3258a900a205b3bcd7a1cd3286b5e8e9340d4158..039f5a4b5d12b777e433f4a2d7e1be22c607a5e4 100644
--- a/src/platform/linux/mod.rs
+++ b/src/platform/linux/mod.rs
@@ -77,9 +77,9 @@ pub fn e(sys: usize) -> usize {
 pub struct Sys;
 
 impl Sys {
-    pub unsafe fn ioctl(fd: c_int, request: c_ulong, out: *mut c_void) -> c_int {
+    pub unsafe fn ioctl(fd: c_int, request: c_ulong, out: *mut c_void) -> Result<c_int> {
         // TODO: Somehow support varargs to syscall??
-        e(syscall!(IOCTL, fd, request, out)) as c_int
+        Ok(e_raw(syscall!(IOCTL, fd, request, out))? as c_int)
     }
 
     // fn times(out: *mut tms) -> clock_t {
@@ -92,8 +92,8 @@ impl Pal for Sys {
         e_raw(unsafe { syscall!(ACCESS, path.as_ptr(), mode) }).map(|_| ())
     }
 
-    unsafe fn brk(addr: *mut c_void) -> *mut c_void {
-        unsafe { syscall!(BRK, addr) as *mut c_void }
+    unsafe fn brk(addr: *mut c_void) -> Result<*mut c_void> {
+        Ok(e_raw(unsafe { syscall!(BRK, addr) })? as *mut c_void)
     }
 
     fn chdir(path: CStr) -> Result<()> {
@@ -144,10 +144,15 @@ impl Pal for Sys {
         e_raw(unsafe { syscall!(DUP3, fildes, fildes2, 0) }).map(|f| f as c_int)
     }
 
-    unsafe fn execve(path: CStr, argv: *const *mut c_char, envp: *const *mut c_char) -> c_int {
-        e(syscall!(EXECVE, path.as_ptr(), argv, envp)) as c_int
+    unsafe fn execve(path: CStr, argv: *const *mut c_char, envp: *const *mut c_char) -> Result<()> {
+        e_raw(syscall!(EXECVE, path.as_ptr(), argv, envp))?;
+        unreachable!()
     }
-    unsafe fn fexecve(fildes: c_int, argv: *const *mut c_char, envp: *const *mut c_char) -> c_int {
+    unsafe fn fexecve(
+        fildes: c_int,
+        argv: *const *mut c_char,
+        envp: *const *mut c_char,
+    ) -> Result<()> {
         todo!("not yet used by relibc")
     }
 
@@ -178,53 +183,50 @@ impl Pal for Sys {
         e_raw(unsafe { syscall!(FDATASYNC, fildes) }).map(|_| ())
     }
 
-    fn flock(fd: c_int, operation: c_int) -> c_int {
-        e(unsafe { syscall!(FLOCK, fd, operation) }) as c_int
+    fn flock(fd: c_int, operation: c_int) -> Result<()> {
+        e_raw(unsafe { syscall!(FLOCK, fd, operation) }).map(|_| ())
     }
 
-    fn fstat(fildes: c_int, buf: *mut stat) -> c_int {
+    unsafe fn fstat(fildes: c_int, buf: *mut stat) -> Result<()> {
         let empty = b"\0";
         let empty_ptr = empty.as_ptr() as *const c_char;
-        e(unsafe { syscall!(NEWFSTATAT, fildes, empty_ptr, buf, AT_EMPTY_PATH) }) as c_int
+        e_raw(unsafe { syscall!(NEWFSTATAT, fildes, empty_ptr, buf, AT_EMPTY_PATH) }).map(|_| ())
     }
 
-    fn fstatvfs(fildes: c_int, buf: *mut statvfs) -> c_int {
+    unsafe fn fstatvfs(fildes: c_int, buf: *mut statvfs) -> Result<()> {
         let mut kbuf = linux_statfs::default();
         let kbuf_ptr = &mut kbuf as *mut linux_statfs;
-        let res = e(unsafe { syscall!(FSTATFS, fildes, kbuf_ptr) }) as c_int;
-        if res == 0 {
-            unsafe {
-                if !buf.is_null() {
-                    (*buf).f_bsize = kbuf.f_bsize as c_ulong;
-                    (*buf).f_frsize = if kbuf.f_frsize != 0 {
-                        kbuf.f_frsize
-                    } else {
-                        kbuf.f_bsize
-                    } as c_ulong;
-                    (*buf).f_blocks = kbuf.f_blocks;
-                    (*buf).f_bfree = kbuf.f_bfree;
-                    (*buf).f_bavail = kbuf.f_bavail;
-                    (*buf).f_files = kbuf.f_files;
-                    (*buf).f_ffree = kbuf.f_ffree;
-                    (*buf).f_favail = kbuf.f_ffree;
-                    (*buf).f_fsid = kbuf.f_fsid as c_ulong;
-                    (*buf).f_flag = kbuf.f_flags as c_ulong;
-                    (*buf).f_namemax = kbuf.f_namelen as c_ulong;
-                }
-            }
+        e_raw(syscall!(FSTATFS, fildes, kbuf_ptr))?;
+
+        if !buf.is_null() {
+            (*buf).f_bsize = kbuf.f_bsize as c_ulong;
+            (*buf).f_frsize = if kbuf.f_frsize != 0 {
+                kbuf.f_frsize
+            } else {
+                kbuf.f_bsize
+            } as c_ulong;
+            (*buf).f_blocks = kbuf.f_blocks;
+            (*buf).f_bfree = kbuf.f_bfree;
+            (*buf).f_bavail = kbuf.f_bavail;
+            (*buf).f_files = kbuf.f_files;
+            (*buf).f_ffree = kbuf.f_ffree;
+            (*buf).f_favail = kbuf.f_ffree;
+            (*buf).f_fsid = kbuf.f_fsid as c_ulong;
+            (*buf).f_flag = kbuf.f_flags as c_ulong;
+            (*buf).f_namemax = kbuf.f_namelen as c_ulong;
         }
-        res
+        Ok(())
     }
 
-    fn fcntl(fildes: c_int, cmd: c_int, arg: c_ulonglong) -> c_int {
-        e(unsafe { syscall!(FCNTL, fildes, cmd, arg) }) as c_int
+    fn fcntl(fildes: c_int, cmd: c_int, arg: c_ulonglong) -> Result<c_int> {
+        Ok(e_raw(unsafe { syscall!(FCNTL, fildes, cmd, arg) })? as c_int)
     }
 
-    fn fork() -> pid_t {
-        e(unsafe { syscall!(CLONE, SIGCHLD, 0, 0, 0, 0) }) as pid_t
+    unsafe fn fork() -> Result<pid_t> {
+        Ok(e_raw(unsafe { syscall!(CLONE, SIGCHLD, 0, 0, 0, 0) })? as pid_t)
     }
 
-    fn fpath(fildes: c_int, out: &mut [u8]) -> Result<ssize_t> {
+    fn fpath(fildes: c_int, out: &mut [u8]) -> Result<usize> {
         let mut proc_path = b"/proc/self/fd/".to_vec();
         write!(proc_path, "{}", fildes).unwrap();
         proc_path.push(0);
@@ -263,20 +265,17 @@ impl Pal for Sys {
         .map(|n| n as u32)
     }
 
-    fn futimens(fd: c_int, times: *const timespec) -> c_int {
-        e(unsafe { syscall!(UTIMENSAT, fd, ptr::null::<c_char>(), times, 0) }) as c_int
+    unsafe fn futimens(fd: c_int, times: *const timespec) -> Result<()> {
+        e_raw(unsafe { syscall!(UTIMENSAT, fd, ptr::null::<c_char>(), times, 0) }).map(|_| ())
     }
 
-    fn utimens(path: CStr, times: *const timespec) -> c_int {
-        e(unsafe { syscall!(UTIMENSAT, AT_FDCWD, path.as_ptr(), times, 0) }) as c_int
+    unsafe fn utimens(path: CStr, times: *const timespec) -> Result<()> {
+        e_raw(unsafe { syscall!(UTIMENSAT, AT_FDCWD, path.as_ptr(), times, 0) }).map(|_| ())
     }
 
-    fn getcwd(buf: *mut c_char, size: size_t) -> *mut c_char {
-        if e(unsafe { syscall!(GETCWD, buf, size) }) == !0 {
-            ptr::null_mut()
-        } else {
-            buf
-        }
+    unsafe fn getcwd(buf: *mut c_char, size: size_t) -> Result<()> {
+        e_raw(unsafe { syscall!(GETCWD, buf, size) })?;
+        Ok(())
     }
 
     fn getdents(fd: c_int, buf: &mut [u8], _off: u64) -> Result<usize> {
@@ -292,43 +291,48 @@ impl Pal for Sys {
     }
 
     fn getegid() -> gid_t {
-        e(unsafe { syscall!(GETEGID) }) as gid_t
+        // Always successful
+        unsafe { syscall!(GETEGID) as gid_t }
     }
 
     fn geteuid() -> uid_t {
-        e(unsafe { syscall!(GETEUID) }) as uid_t
+        // Always successful
+        unsafe { syscall!(GETEUID) as uid_t }
     }
 
     fn getgid() -> gid_t {
-        e(unsafe { syscall!(GETGID) }) as gid_t
+        // Always successful
+        unsafe { syscall!(GETGID) as gid_t }
     }
 
-    unsafe fn getgroups(size: c_int, list: *mut gid_t) -> c_int {
-        e(unsafe { syscall!(GETGROUPS, size, list) }) as c_int
+    unsafe fn getgroups(size: c_int, list: *mut gid_t) -> Result<c_int> {
+        Ok(e_raw(unsafe { syscall!(GETGROUPS, size, list) })? as c_int)
     }
 
     fn getpagesize() -> usize {
         4096
     }
 
-    fn getpgid(pid: pid_t) -> pid_t {
-        e(unsafe { syscall!(GETPGID, pid) }) as pid_t
+    fn getpgid(pid: pid_t) -> Result<pid_t> {
+        Ok(e_raw(unsafe { syscall!(GETPGID, pid) })? as pid_t)
     }
 
     fn getpid() -> pid_t {
-        e(unsafe { syscall!(GETPID) }) as pid_t
+        // Always successful
+        unsafe { syscall!(GETPID) as pid_t }
     }
 
     fn getppid() -> pid_t {
-        e(unsafe { syscall!(GETPPID) }) as pid_t
+        // Always successful
+        unsafe { syscall!(GETPPID) as pid_t }
     }
 
-    fn getpriority(which: c_int, who: id_t) -> c_int {
-        e(unsafe { syscall!(GETPRIORITY, which, who) }) as c_int
+    fn getpriority(which: c_int, who: id_t) -> Result<c_int> {
+        Ok(e_raw(unsafe { syscall!(GETPRIORITY, which, who) })? as c_int)
     }
 
-    fn getrandom(buf: &mut [u8], flags: c_uint) -> ssize_t {
-        e(unsafe { syscall!(GETRANDOM, buf.as_mut_ptr(), buf.len(), flags) }) as ssize_t
+    fn getrandom(buf: &mut [u8], flags: c_uint) -> Result<usize> {
+        e_raw(unsafe { syscall!(GETRANDOM, buf.as_mut_ptr(), buf.len(), flags) })
     }
 
     unsafe fn getrlimit(resource: c_int, rlim: *mut rlimit) -> Result<()> {
@@ -339,24 +343,26 @@ impl Pal for Sys {
         e_raw(syscall!(SETRLIMIT, resource, rlimit)).map(|_| ())
     }
 
-    fn getrusage(who: c_int, r_usage: &mut rusage) -> c_int {
-        e(unsafe { syscall!(GETRUSAGE, who, r_usage as *mut rusage) }) as c_int
+    fn getrusage(who: c_int, r_usage: &mut rusage) -> Result<()> {
+        e_raw(unsafe { syscall!(GETRUSAGE, who, r_usage as *mut rusage) })?;
+        Ok(())
     }
 
-    fn getsid(pid: pid_t) -> pid_t {
-        e(unsafe { syscall!(GETSID, pid) }) as pid_t
+    fn getsid(pid: pid_t) -> Result<pid_t> {
+        Ok(e_raw(unsafe { syscall!(GETSID, pid) })? as pid_t)
     }
 
     fn gettid() -> pid_t {
-        e(unsafe { syscall!(GETTID) }) as pid_t
+        // Always successful
+        unsafe { syscall!(GETTID) as pid_t }
     }
 
-    fn gettimeofday(tp: *mut timeval, tzp: *mut timezone) -> c_int {
-        e(unsafe { syscall!(GETTIMEOFDAY, tp, tzp) }) as c_int
+    unsafe fn gettimeofday(tp: *mut timeval, tzp: *mut timezone) -> Result<()> {
+        e_raw(unsafe { syscall!(GETTIMEOFDAY, tp, tzp) }).map(|_| ())
     }
 
     fn getuid() -> uid_t {
-        e(unsafe { syscall!(GETUID) }) as uid_t
+        unsafe { syscall!(GETUID) as uid_t }
     }
 
     fn lchown(path: CStr, owner: uid_t, group: gid_t) -> Result<()> {
@@ -404,12 +410,12 @@ impl Pal for Sys {
         Sys::mknod(path, mode | S_IFIFO, 0)
     }
 
-    unsafe fn mlock(addr: *const c_void, len: usize) -> c_int {
-        e(syscall!(MLOCK, addr, len)) as c_int
+    unsafe fn mlock(addr: *const c_void, len: usize) -> Result<()> {
+        e_raw(unsafe { syscall!(MLOCK, addr, len) }).map(|_| ())
     }
 
-    fn mlockall(flags: c_int) -> c_int {
-        e(unsafe { syscall!(MLOCKALL, flags) }) as c_int
+    unsafe fn mlockall(flags: c_int) -> Result<()> {
+        e_raw(unsafe { syscall!(MLOCKALL, flags) }).map(|_| ())
     }
 
     unsafe fn mmap(
@@ -419,8 +425,8 @@ impl Pal for Sys {
         flags: c_int,
         fildes: c_int,
         off: off_t,
-    ) -> *mut c_void {
-        e(syscall!(MMAP, addr, len, prot, flags, fildes, off)) as *mut c_void
+    ) -> Result<*mut c_void> {
+        Ok(e_raw(syscall!(MMAP, addr, len, prot, flags, fildes, off))? as *mut c_void)
     }
 
     unsafe fn mremap(
@@ -429,36 +435,36 @@ impl Pal for Sys {
         new_len: usize,
         flags: c_int,
         args: *mut c_void,
-    ) -> *mut c_void {
-        e(syscall!(MREMAP, addr, len, new_len, flags, args)) as *mut c_void
+    ) -> Result<*mut c_void> {
+        Ok(e_raw(syscall!(MREMAP, addr, len, new_len, flags, args))? as *mut c_void)
     }
 
-    unsafe fn mprotect(addr: *mut c_void, len: usize, prot: c_int) -> c_int {
-        e(syscall!(MPROTECT, addr, len, prot)) as c_int
+    unsafe fn mprotect(addr: *mut c_void, len: usize, prot: c_int) -> Result<()> {
+        e_raw(syscall!(MPROTECT, addr, len, prot)).map(|_| ())
     }
 
-    unsafe fn msync(addr: *mut c_void, len: usize, flags: c_int) -> c_int {
-        e(syscall!(MSYNC, addr, len, flags)) as c_int
+    unsafe fn msync(addr: *mut c_void, len: usize, flags: c_int) -> Result<()> {
+        e_raw(syscall!(MSYNC, addr, len, flags)).map(|_| ())
     }
 
-    unsafe fn munlock(addr: *const c_void, len: usize) -> c_int {
-        e(syscall!(MUNLOCK, addr, len)) as c_int
+    unsafe fn munlock(addr: *const c_void, len: usize) -> Result<()> {
+        e_raw(syscall!(MUNLOCK, addr, len)).map(|_| ())
     }
 
-    fn munlockall() -> c_int {
-        e(unsafe { syscall!(MUNLOCKALL) }) as c_int
+    unsafe fn munlockall() -> Result<()> {
+        e_raw(unsafe { syscall!(MUNLOCKALL) }).map(|_| ())
     }
 
-    unsafe fn munmap(addr: *mut c_void, len: usize) -> c_int {
-        e(syscall!(MUNMAP, addr, len)) as c_int
+    unsafe fn munmap(addr: *mut c_void, len: usize) -> Result<()> {
+        e_raw(syscall!(MUNMAP, addr, len)).map(|_| ())
     }
 
-    unsafe fn madvise(addr: *mut c_void, len: usize, flags: c_int) -> c_int {
-        e(syscall!(MADVISE, addr, len, flags)) as c_int
+    unsafe fn madvise(addr: *mut c_void, len: usize, flags: c_int) -> Result<()> {
+        e_raw(syscall!(MADVISE, addr, len, flags)).map(|_| ())
     }
 
-    fn nanosleep(rqtp: *const timespec, rmtp: *mut timespec) -> c_int {
-        e(unsafe { syscall!(NANOSLEEP, rqtp, rmtp) }) as c_int
+    unsafe fn nanosleep(rqtp: *const timespec, rmtp: *mut timespec) -> Result<()> {
+        e_raw(unsafe { syscall!(NANOSLEEP, rqtp, rmtp) }).map(|_| ())
     }
 
     fn open(path: CStr, oflag: c_int, mode: mode_t) -> Result<c_int> {
@@ -534,17 +540,14 @@ impl Pal for Sys {
         }
     }
 
-    fn read(fildes: c_int, buf: &mut [u8]) -> Result<ssize_t> {
-        Ok(e_raw(unsafe { syscall!(READ, fildes, buf.as_mut_ptr(), buf.len()) })? as ssize_t)
+    fn read(fildes: c_int, buf: &mut [u8]) -> Result<usize> {
+        e_raw(unsafe { syscall!(READ, fildes, buf.as_mut_ptr(), buf.len()) })
     }
-    fn pread(fildes: c_int, buf: &mut [u8], off: off_t) -> Result<ssize_t> {
-        Ok(
-            e_raw(unsafe { syscall!(PREAD64, fildes, buf.as_mut_ptr(), buf.len(), off) })?
-                as ssize_t,
-        )
+    fn pread(fildes: c_int, buf: &mut [u8], off: off_t) -> Result<usize> {
+        e_raw(unsafe { syscall!(PREAD64, fildes, buf.as_mut_ptr(), buf.len(), off) })
     }
 
-    fn readlink(pathname: CStr, out: &mut [u8]) -> Result<ssize_t> {
+    fn readlink(pathname: CStr, out: &mut [u8]) -> Result<usize> {
         e_raw(unsafe {
             syscall!(
                 READLINKAT,
@@ -554,7 +557,6 @@ impl Pal for Sys {
                 out.len()
             )
         })
-        .map(|b| b as ssize_t)
     }
 
     fn rename(old: CStr, new: CStr) -> Result<()> {
@@ -614,19 +616,19 @@ impl Pal for Sys {
         e_raw(unsafe { syscall!(UNLINKAT, AT_FDCWD, path.as_ptr(), 0) }).map(|_| ())
     }
 
-    fn waitpid(pid: pid_t, stat_loc: *mut c_int, options: c_int) -> pid_t {
-        e(unsafe { syscall!(WAIT4, pid, stat_loc, options, 0) }) as pid_t
+    unsafe fn waitpid(pid: pid_t, stat_loc: *mut c_int, options: c_int) -> Result<pid_t> {
+        e_raw(unsafe { syscall!(WAIT4, pid, stat_loc, options, 0) }).map(|p| p as pid_t)
     }
 
-    fn write(fildes: c_int, buf: &[u8]) -> Result<ssize_t> {
-        Ok(e_raw(unsafe { syscall!(WRITE, fildes, buf.as_ptr(), buf.len()) })? as ssize_t)
+    fn write(fildes: c_int, buf: &[u8]) -> Result<usize> {
+        e_raw(unsafe { syscall!(WRITE, fildes, buf.as_ptr(), buf.len()) })
     }
-    fn pwrite(fildes: c_int, buf: &[u8], off: off_t) -> Result<ssize_t> {
-        Ok(e_raw(unsafe { syscall!(PWRITE64, fildes, buf.as_ptr(), buf.len(), off) })? as ssize_t)
+    fn pwrite(fildes: c_int, buf: &[u8], off: off_t) -> Result<usize> {
+        e_raw(unsafe { syscall!(PWRITE64, fildes, buf.as_ptr(), buf.len(), off) })
     }
 
     fn verify() -> bool {
         // GETPID on Linux is 39, which does not exist on Redox
-        e(unsafe { sc::syscall5(sc::nr::GETPID, !0, !0, !0, !0, !0) }) != !0
+        e_raw(unsafe { sc::syscall5(sc::nr::GETPID, !0, !0, !0, !0, !0) }).is_ok()
     }
 }
diff --git a/src/platform/linux/signal.rs b/src/platform/linux/signal.rs
index 7a379e06af65d94d7ee6a88daa5c46a34273bb81..10cefc820000249e6c1309f338f65dd8bcd90c43 100644
--- a/src/platform/linux/signal.rs
+++ b/src/platform/linux/signal.rs
@@ -6,7 +6,7 @@ use super::{
     e, e_raw, Sys,
 };
 use crate::{
-    error::Errno,
+    error::{Errno, Result},
     header::{
         signal::{sigaction, siginfo_t, sigset_t, stack_t, NSIG, SA_RESTORER, SI_QUEUE},
         sys_time::itimerval,
@@ -57,14 +57,16 @@ pub struct mcontext_t {
 }
 
 impl PalSignal for Sys {
-    unsafe fn getitimer(which: c_int, out: *mut itimerval) -> c_int {
-        e(syscall!(GETITIMER, which, out)) as c_int
+    unsafe fn getitimer(which: c_int, out: *mut itimerval) -> Result<()> {
+        e_raw(syscall!(GETITIMER, which, out))?;
+        Ok(())
     }
 
-    fn kill(pid: pid_t, sig: c_int) -> c_int {
-        e(unsafe { syscall!(KILL, pid, sig) }) as c_int
+    fn kill(pid: pid_t, sig: c_int) -> Result<()> {
+        e_raw(unsafe { syscall!(KILL, pid, sig) })?;
+        Ok(())
     }
-    fn sigqueue(pid: pid_t, sig: c_int, val: sigval) -> Result<(), Errno> {
+    fn sigqueue(pid: pid_t, sig: c_int, val: sigval) -> Result<()> {
         let info = siginfo_t {
             si_addr: core::ptr::null_mut(),
             si_code: SI_QUEUE,
@@ -78,18 +80,20 @@ impl PalSignal for Sys {
         e_raw(unsafe { syscall!(RT_SIGQUEUEINFO, pid, sig, addr_of!(info)) }).map(|_| ())
     }
 
-    fn killpg(pgrp: pid_t, sig: c_int) -> c_int {
-        e(unsafe { syscall!(KILL, -(pgrp as isize) as pid_t, sig) }) as c_int
+    fn killpg(pgrp: pid_t, sig: c_int) -> Result<()> {
+        e_raw(unsafe { syscall!(KILL, -(pgrp as isize) as pid_t, sig) })?;
+        Ok(())
     }
 
-    fn raise(sig: c_int) -> Result<(), Errno> {
+    fn raise(sig: c_int) -> Result<()> {
         let tid = e_raw(unsafe { syscall!(GETTID) })? as pid_t;
         e_raw(unsafe { syscall!(TKILL, tid, sig) })?;
         Ok(())
     }
 
-    unsafe fn setitimer(which: c_int, new: *const itimerval, old: *mut itimerval) -> c_int {
-        e(syscall!(SETITIMER, which, new, old)) as c_int
+    unsafe fn setitimer(which: c_int, new: *const itimerval, old: *mut itimerval) -> Result<()> {
+        e_raw(unsafe { syscall!(SETITIMER, which, new, old) })?;
+        Ok(())
     }
 
     fn sigaction(
@@ -118,7 +122,7 @@ impl PalSignal for Sys {
         .map(|_| ())
     }
 
-    unsafe fn sigaltstack(ss: Option<&stack_t>, old_ss: Option<&mut stack_t>) -> Result<(), Errno> {
+    unsafe fn sigaltstack(ss: Option<&stack_t>, old_ss: Option<&mut stack_t>) -> Result<()> {
         e_raw(syscall!(
             SIGALTSTACK,
             ss.map_or_else(core::ptr::null, |x| x as *const _),
@@ -127,7 +131,7 @@ impl PalSignal for Sys {
         .map(|_| ())
     }
 
-    fn sigpending(set: &mut sigset_t) -> Result<(), Errno> {
+    fn sigpending(set: &mut sigset_t) -> Result<()> {
         e_raw(unsafe {
             syscall!(
                 RT_SIGPENDING,
@@ -138,11 +142,7 @@ impl PalSignal for Sys {
         .map(|_| ())
     }
 
-    fn sigprocmask(
-        how: c_int,
-        set: Option<&sigset_t>,
-        oset: Option<&mut sigset_t>,
-    ) -> Result<(), Errno> {
+    fn sigprocmask(how: c_int, set: Option<&sigset_t>, oset: Option<&mut sigset_t>) -> Result<()> {
         e_raw(unsafe {
             syscall!(
                 RT_SIGPROCMASK,
@@ -166,7 +166,7 @@ impl PalSignal for Sys {
         set: &sigset_t,
         sig: Option<&mut siginfo_t>,
         tp: Option<&timespec>,
-    ) -> Result<(), Errno> {
+    ) -> Result<()> {
         unsafe {
             e_raw(syscall!(
                 RT_SIGTIMEDWAIT,
diff --git a/src/platform/mod.rs b/src/platform/mod.rs
index 9b51834582fb2997ae606854237405abcd49ae12..d94cdb7e46df0f7d76913fe326fb54f2387aa5ef 100644
--- a/src/platform/mod.rs
+++ b/src/platform/mod.rs
@@ -86,7 +86,9 @@ pub struct FileWriter(pub c_int);
 
 impl FileWriter {
     pub fn write(&mut self, buf: &[u8]) -> isize {
-        Sys::write(self.0, buf).or_minus_one_errno()
+        Sys::write(self.0, buf)
+            .map(|u| u as isize)
+            .or_minus_one_errno()
     }
 }
 
@@ -107,14 +109,19 @@ impl WriteByte for FileWriter {
 pub struct FileReader(pub c_int);
 
 impl FileReader {
+    // TODO: This is a bad interface. Rustify
     pub fn read(&mut self, buf: &mut [u8]) -> isize {
-        Sys::read(self.0, buf).or_minus_one_errno()
+        Sys::read(self.0, buf)
+            .map(|u| u as isize)
+            .or_minus_one_errno()
     }
 }
 
 impl Read for FileReader {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        let i = Sys::read(self.0, buf).or_minus_one_errno(); // TODO
+        let i = Sys::read(self.0, buf)
+            .map(|u| u as isize)
+            .or_minus_one_errno(); // TODO
         if i >= 0 {
             Ok(i as usize)
         } else {
diff --git a/src/platform/pal/epoll.rs b/src/platform/pal/epoll.rs
index 6162368b384f481cf9fdffb7688dfd9d47cbc0a5..3d72f566ce083e522508e64f9f41d02356a92768 100644
--- a/src/platform/pal/epoll.rs
+++ b/src/platform/pal/epoll.rs
@@ -1,14 +1,17 @@
-use super::super::{types::*, Pal};
-use crate::header::{signal::sigset_t, sys_epoll::epoll_event};
+use crate::{
+    error::{Errno, Result},
+    header::{signal::sigset_t, sys_epoll::epoll_event},
+    platform::{types::*, Pal},
+};
 
 pub trait PalEpoll: Pal {
-    fn epoll_create1(flags: c_int) -> c_int;
-    fn epoll_ctl(epfd: c_int, op: c_int, fd: c_int, event: *mut epoll_event) -> c_int;
-    fn epoll_pwait(
+    fn epoll_create1(flags: c_int) -> Result<c_int>;
+    unsafe fn epoll_ctl(epfd: c_int, op: c_int, fd: c_int, event: *mut epoll_event) -> Result<()>;
+    unsafe fn epoll_pwait(
         epfd: c_int,
         events: *mut epoll_event,
         maxevents: c_int,
         timeout: c_int,
         sigmask: *const sigset_t,
-    ) -> c_int;
+    ) -> Result<usize>;
 }
diff --git a/src/platform/pal/mod.rs b/src/platform/pal/mod.rs
index e8716defdea9e06d38a38c1147286add0b8ee2c7..c80069001e1038bb4af63ea7ab25df9d095d18be 100644
--- a/src/platform/pal/mod.rs
+++ b/src/platform/pal/mod.rs
@@ -28,7 +28,7 @@ mod socket;
 pub trait Pal {
     fn access(path: CStr, mode: c_int) -> Result<()>;
 
-    unsafe fn brk(addr: *mut c_void) -> *mut c_void;
+    unsafe fn brk(addr: *mut c_void) -> Result<*mut c_void>;
 
     fn chdir(path: CStr) -> Result<()>;
 
@@ -50,8 +50,12 @@ pub trait Pal {
 
     fn dup2(fildes: c_int, fildes2: c_int) -> Result<c_int>;
 
-    unsafe fn execve(path: CStr, argv: *const *mut c_char, envp: *const *mut c_char) -> c_int;
-    unsafe fn fexecve(fildes: c_int, argv: *const *mut c_char, envp: *const *mut c_char) -> c_int;
+    unsafe fn execve(path: CStr, argv: *const *mut c_char, envp: *const *mut c_char) -> Result<()>;
+    unsafe fn fexecve(
+        fildes: c_int,
+        argv: *const *mut c_char,
+        envp: *const *mut c_char,
+    ) -> Result<()>;
 
     fn exit(status: c_int) -> !;
 
@@ -65,17 +69,17 @@ pub trait Pal {
 
     fn fdatasync(fildes: c_int) -> Result<()>;
 
-    fn flock(fd: c_int, operation: c_int) -> c_int;
+    fn flock(fd: c_int, operation: c_int) -> Result<()>;
 
-    fn fstat(fildes: c_int, buf: *mut stat) -> c_int;
+    unsafe fn fstat(fildes: c_int, buf: *mut stat) -> Result<()>;
 
-    fn fstatvfs(fildes: c_int, buf: *mut statvfs) -> c_int;
+    unsafe fn fstatvfs(fildes: c_int, buf: *mut statvfs) -> Result<()>;
 
-    fn fcntl(fildes: c_int, cmd: c_int, arg: c_ulonglong) -> c_int;
+    fn fcntl(fildes: c_int, cmd: c_int, arg: c_ulonglong) -> Result<c_int>;
 
-    fn fork() -> pid_t;
+    unsafe fn fork() -> Result<pid_t>;
 
-    fn fpath(fildes: c_int, out: &mut [u8]) -> Result<ssize_t>;
+    fn fpath(fildes: c_int, out: &mut [u8]) -> Result<usize>;
 
     fn fsync(fildes: c_int) -> Result<()>;
 
@@ -84,11 +88,11 @@ pub trait Pal {
     unsafe fn futex_wait(addr: *mut u32, val: u32, deadline: Option<&timespec>) -> Result<()>;
     unsafe fn futex_wake(addr: *mut u32, num: u32) -> Result<u32>;
 
-    fn futimens(fd: c_int, times: *const timespec) -> c_int;
+    unsafe fn futimens(fd: c_int, times: *const timespec) -> Result<()>;
 
-    fn utimens(path: CStr, times: *const timespec) -> c_int;
+    unsafe fn utimens(path: CStr, times: *const timespec) -> Result<()>;
 
-    fn getcwd(buf: *mut c_char, size: size_t) -> *mut c_char;
+    unsafe fn getcwd(buf: *mut c_char, size: size_t) -> Result<()>;
 
     fn getdents(fd: c_int, buf: &mut [u8], opaque_offset: u64) -> Result<usize>;
     fn dir_seek(fd: c_int, opaque_offset: u64) -> Result<()>;
@@ -98,40 +102,46 @@ pub trait Pal {
     // possible this_dent slice is safe (and will be validated).
     unsafe fn dent_reclen_offset(this_dent: &[u8], offset: usize) -> Option<(u16, u64)>;
 
+    // Always successful
     fn getegid() -> gid_t;
 
+    // Always successful
     fn geteuid() -> uid_t;
 
+    // Always successful
     fn getgid() -> gid_t;
 
-    unsafe fn getgroups(size: c_int, list: *mut gid_t) -> c_int;
+    unsafe fn getgroups(size: c_int, list: *mut gid_t) -> Result<c_int>;
 
     /* Note that this is distinct from the legacy POSIX function
      * getpagesize(), which returns a c_int. On some Linux platforms,
      * page size may be determined through a syscall ("getpagesize"). */
     fn getpagesize() -> usize;
 
-    fn getpgid(pid: pid_t) -> pid_t;
+    fn getpgid(pid: pid_t) -> Result<pid_t>;
 
+    // Always successful
     fn getpid() -> pid_t;
 
+    // Always successful
     fn getppid() -> pid_t;
 
-    fn getpriority(which: c_int, who: id_t) -> c_int;
+    fn getpriority(which: c_int, who: id_t) -> Result<c_int>;
 
-    fn getrandom(buf: &mut [u8], flags: c_uint) -> ssize_t;
+    fn getrandom(buf: &mut [u8], flags: c_uint) -> Result<usize>;
 
     unsafe fn getrlimit(resource: c_int, rlim: *mut rlimit) -> Result<()>;
 
     unsafe fn setrlimit(resource: c_int, rlim: *const rlimit) -> Result<()>;
 
-    fn getrusage(who: c_int, r_usage: &mut rusage) -> c_int;
+    fn getrusage(who: c_int, r_usage: &mut rusage) -> Result<()>;
 
-    fn getsid(pid: pid_t) -> pid_t;
+    fn getsid(pid: pid_t) -> Result<pid_t>;
 
+    // Always successful
     fn gettid() -> pid_t;
 
-    fn gettimeofday(tp: *mut timeval, tzp: *mut timezone) -> c_int;
+    unsafe fn gettimeofday(tp: *mut timeval, tzp: *mut timezone) -> Result<()>;
 
     fn getuid() -> uid_t;
 
@@ -149,9 +159,9 @@ pub trait Pal {
 
     fn mknod(path: CStr, mode: mode_t, dev: dev_t) -> Result<()>;
 
-    unsafe fn mlock(addr: *const c_void, len: usize) -> c_int;
+    unsafe fn mlock(addr: *const c_void, len: usize) -> Result<()>;
 
-    fn mlockall(flags: c_int) -> c_int;
+    unsafe fn mlockall(flags: c_int) -> Result<()>;
 
     unsafe fn mmap(
         addr: *mut c_void,
@@ -160,7 +170,7 @@ pub trait Pal {
         flags: c_int,
         fildes: c_int,
         off: off_t,
-    ) -> *mut c_void;
+    ) -> Result<*mut c_void>;
 
     unsafe fn mremap(
         addr: *mut c_void,
@@ -168,21 +178,21 @@ pub trait Pal {
         new_len: usize,
         flags: c_int,
         args: *mut c_void,
-    ) -> *mut c_void;
+    ) -> Result<*mut c_void>;
 
-    unsafe fn mprotect(addr: *mut c_void, len: usize, prot: c_int) -> c_int;
+    unsafe fn mprotect(addr: *mut c_void, len: usize, prot: c_int) -> Result<()>;
 
-    unsafe fn msync(addr: *mut c_void, len: usize, flags: c_int) -> c_int;
+    unsafe fn msync(addr: *mut c_void, len: usize, flags: c_int) -> Result<()>;
 
-    unsafe fn munlock(addr: *const c_void, len: usize) -> c_int;
+    unsafe fn munlock(addr: *const c_void, len: usize) -> Result<()>;
 
-    unsafe fn madvise(addr: *mut c_void, len: usize, flags: c_int) -> c_int;
+    unsafe fn madvise(addr: *mut c_void, len: usize, flags: c_int) -> Result<()>;
 
-    fn munlockall() -> c_int;
+    unsafe fn munlockall() -> Result<()>;
 
-    unsafe fn munmap(addr: *mut c_void, len: usize) -> c_int;
+    unsafe fn munmap(addr: *mut c_void, len: usize) -> Result<()>;
 
-    fn nanosleep(rqtp: *const timespec, rmtp: *mut timespec) -> c_int;
+    unsafe fn nanosleep(rqtp: *const timespec, rmtp: *mut timespec) -> Result<()>;
 
     fn open(path: CStr, oflag: c_int, mode: mode_t) -> Result<c_int>;
 
@@ -193,10 +203,10 @@ pub trait Pal {
 
     fn current_os_tid() -> pthread::OsTid;
 
-    fn read(fildes: c_int, buf: &mut [u8]) -> Result<ssize_t>;
-    fn pread(fildes: c_int, buf: &mut [u8], offset: off_t) -> Result<ssize_t>;
+    fn read(fildes: c_int, buf: &mut [u8]) -> Result<usize>;
+    fn pread(fildes: c_int, buf: &mut [u8], offset: off_t) -> Result<usize>;
 
-    fn readlink(pathname: CStr, out: &mut [u8]) -> Result<ssize_t>;
+    fn readlink(pathname: CStr, out: &mut [u8]) -> Result<usize>;
 
     fn rename(old: CStr, new: CStr) -> Result<()>;
 
@@ -220,16 +230,17 @@ pub trait Pal {
 
     fn sync() -> Result<()>;
 
+    // Always successful
     fn umask(mask: mode_t) -> mode_t;
 
     unsafe fn uname(utsname: *mut utsname) -> Result<()>;
 
     fn unlink(path: CStr) -> Result<()>;
 
-    fn waitpid(pid: pid_t, stat_loc: *mut c_int, options: c_int) -> pid_t;
+    unsafe fn waitpid(pid: pid_t, stat_loc: *mut c_int, options: c_int) -> Result<pid_t>;
 
-    fn write(fildes: c_int, buf: &[u8]) -> Result<ssize_t>;
-    fn pwrite(fildes: c_int, buf: &[u8], offset: off_t) -> Result<ssize_t>;
+    fn write(fildes: c_int, buf: &[u8]) -> Result<usize>;
+    fn pwrite(fildes: c_int, buf: &[u8], offset: off_t) -> Result<usize>;
 
     fn verify() -> bool;
 }
diff --git a/src/platform/pal/signal.rs b/src/platform/pal/signal.rs
index 7a01780ac15301d57028803ce22ace6c870f2714..695dcb65d97680865714815988e7d3c946fc5f3e 100644
--- a/src/platform/pal/signal.rs
+++ b/src/platform/pal/signal.rs
@@ -1,6 +1,6 @@
 use super::super::{types::*, Pal};
 use crate::{
-    error::Errno,
+    error::{Errno, Result},
     header::{
         signal::{sigaction, siginfo_t, sigset_t, sigval, stack_t},
         sys_time::itimerval,
@@ -9,33 +9,25 @@ use crate::{
 };
 
 pub trait PalSignal: Pal {
-    unsafe fn getitimer(which: c_int, out: *mut itimerval) -> c_int;
+    unsafe fn getitimer(which: c_int, out: *mut itimerval) -> Result<()>;
 
-    fn kill(pid: pid_t, sig: c_int) -> c_int;
+    fn kill(pid: pid_t, sig: c_int) -> Result<()>;
 
-    fn sigqueue(pid: pid_t, sig: c_int, val: sigval) -> Result<(), Errno>;
+    fn sigqueue(pid: pid_t, sig: c_int, val: sigval) -> Result<()>;
 
-    fn killpg(pgrp: pid_t, sig: c_int) -> c_int;
+    fn killpg(pgrp: pid_t, sig: c_int) -> Result<()>;
 
-    fn raise(sig: c_int) -> Result<(), Errno>;
+    fn raise(sig: c_int) -> Result<()>;
 
-    unsafe fn setitimer(which: c_int, new: *const itimerval, old: *mut itimerval) -> c_int;
+    unsafe fn setitimer(which: c_int, new: *const itimerval, old: *mut itimerval) -> Result<()>;
 
-    fn sigaction(
-        sig: c_int,
-        act: Option<&sigaction>,
-        oact: Option<&mut sigaction>,
-    ) -> Result<(), Errno>;
+    fn sigaction(sig: c_int, act: Option<&sigaction>, oact: Option<&mut sigaction>) -> Result<()>;
 
-    unsafe fn sigaltstack(ss: Option<&stack_t>, old_ss: Option<&mut stack_t>) -> Result<(), Errno>;
+    unsafe fn sigaltstack(ss: Option<&stack_t>, old_ss: Option<&mut stack_t>) -> Result<()>;
 
-    fn sigpending(set: &mut sigset_t) -> Result<(), Errno>;
+    fn sigpending(set: &mut sigset_t) -> Result<()>;
 
-    fn sigprocmask(
-        how: c_int,
-        set: Option<&sigset_t>,
-        oset: Option<&mut sigset_t>,
-    ) -> Result<(), Errno>;
+    fn sigprocmask(how: c_int, set: Option<&sigset_t>, oset: Option<&mut sigset_t>) -> Result<()>;
 
     fn sigsuspend(mask: &sigset_t) -> Errno; // always fails
 
@@ -43,5 +35,5 @@ pub trait PalSignal: Pal {
         set: &sigset_t,
         sig: Option<&mut siginfo_t>,
         tp: Option<&timespec>,
-    ) -> Result<(), Errno>;
+    ) -> Result<()>;
 }
diff --git a/src/platform/redox/epoll.rs b/src/platform/redox/epoll.rs
index 25521854d62ced4dc7e1ea6860e019b46c64249c..89adbbf8f6cd21aa9242536c340d136fe7666cfc 100644
--- a/src/platform/redox/epoll.rs
+++ b/src/platform/redox/epoll.rs
@@ -4,7 +4,7 @@ use super::{
 };
 
 use crate::{
-    error::ResultExt,
+    error::{Errno, ResultExt},
     fs::File,
     header::{errno::*, fcntl::*, signal::sigset_t, sys_epoll::*},
     io::prelude::*,
@@ -52,14 +52,19 @@ fn event_flags_to_epoll(flags: syscall::EventFlags) -> c_uint {
 }
 
 impl PalEpoll for Sys {
-    fn epoll_create1(flags: c_int) -> c_int {
-        Sys::open(c_str!("/scheme/event"), O_RDWR | flags, 0).or_minus_one_errno()
+    fn epoll_create1(flags: c_int) -> Result<c_int, Errno> {
+        Sys::open(c_str!("/scheme/event"), O_RDWR | flags, 0)
     }
 
-    fn epoll_ctl(epfd: c_int, op: c_int, fd: c_int, event: *mut epoll_event) -> c_int {
+    unsafe fn epoll_ctl(
+        epfd: c_int,
+        op: c_int,
+        fd: c_int,
+        event: *mut epoll_event,
+    ) -> Result<(), Errno> {
         match op {
             EPOLL_CTL_ADD | EPOLL_CTL_MOD => {
-                if Sys::write(
+                Sys::write(
                     epfd,
                     &Event {
                         id: fd as usize,
@@ -68,17 +73,10 @@ impl PalEpoll for Sys {
                         // systems. If this is needed, use a box or something
                         data: unsafe { (*event).data.u64 as usize },
                     },
-                )
-                .or_minus_one_errno()
-                    < 0
-                {
-                    -1
-                } else {
-                    0
-                }
+                )?;
             }
             EPOLL_CTL_DEL => {
-                if Sys::write(
+                Sys::write(
                     epfd,
                     &Event {
                         id: fd as usize,
@@ -86,68 +84,49 @@ impl PalEpoll for Sys {
                         //TODO: Is data required?
                         data: 0,
                     },
-                )
-                .or_minus_one_errno()
-                    < 0
-                {
-                    -1
-                } else {
-                    0
-                }
-            }
-            _ => {
-                platform::ERRNO.set(EINVAL);
-                -1
+                )?;
             }
+            _ => return Err(Errno(EINVAL)),
         }
+        Ok(())
     }
 
-    fn epoll_pwait(
+    unsafe fn epoll_pwait(
         epfd: c_int,
         events: *mut epoll_event,
         maxevents: c_int,
         timeout: c_int,
         _sigset: *const sigset_t,
-    ) -> c_int {
+    ) -> Result<usize, Errno> {
         // TODO: sigset
         assert_eq!(mem::size_of::<epoll_event>(), mem::size_of::<Event>());
 
         if maxevents <= 0 {
-            platform::ERRNO.set(EINVAL);
-            return -1;
+            return Err(Errno(EINVAL));
         }
 
         let timer_opt = if timeout != -1 {
-            match File::open(c_str!("/scheme/time/4"), O_RDWR) {
-                Err(_) => return -1,
-                Ok(mut timer) => {
-                    if Sys::write(
-                        epfd,
-                        &Event {
-                            id: timer.fd as usize,
-                            flags: EVENT_READ,
-                            data: 0,
-                        },
-                    )
-                    .or_minus_one_errno()
-                        == -1
-                    {
-                        return -1;
-                    }
-
-                    let mut time = TimeSpec::default();
-                    if let Err(err) = timer.read(&mut time) {
-                        return -1;
-                    }
-                    time.tv_sec += (timeout as i64) / 1000;
-                    time.tv_nsec += (timeout % 1000) * 1000000;
-                    if let Err(err) = timer.write(&time) {
-                        return -1;
-                    }
-
-                    Some(timer)
-                }
-            }
+            let mut timer = File::open(c_str!("/scheme/time/4"), O_RDWR)?;
+            Sys::write(
+                epfd,
+                &Event {
+                    id: timer.fd as usize,
+                    flags: EVENT_READ,
+                    data: 0,
+                },
+            )?;
+
+            let mut time = TimeSpec::default();
+            let _ = timer
+                .read(&mut time)
+                .map_err(|err| Errno(err.raw_os_error().unwrap_or(EIO)))?;
+            time.tv_sec += (timeout as i64) / 1000;
+            time.tv_nsec += (timeout % 1000) * 1000000;
+            let _ = timer
+                .write(&time)
+                .map_err(|err| Errno(err.raw_os_error().unwrap_or(EIO)))?;
+
+            Some(timer)
         } else {
             None
         };
@@ -157,11 +136,7 @@ impl PalEpoll for Sys {
                 events as *mut u8,
                 maxevents as usize * mem::size_of::<syscall::Event>(),
             )
-        })
-        .or_minus_one_errno(); // TODO
-        if bytes_read == -1 {
-            return -1;
-        }
+        })?;
         let read = bytes_read as usize / mem::size_of::<syscall::Event>();
 
         let mut count = 0;
@@ -187,6 +162,6 @@ impl PalEpoll for Sys {
             }
         }
 
-        count as c_int
+        Ok(count)
     }
 }
diff --git a/src/platform/redox/mod.rs b/src/platform/redox/mod.rs
index 62cfab1ac94e36a6d9d5a3dbecbab982109e24b3..94fcfac5fb7b807049969cec1763b1276c01e7e7 100644
--- a/src/platform/redox/mod.rs
+++ b/src/platform/redox/mod.rs
@@ -74,6 +74,7 @@ macro_rules! path_from_c_str {
 
 use self::{exec::Executable, path::canonicalize};
 
+// TODO: Remove
 pub fn e(sys: syscall::error::Result<usize>) -> usize {
     match sys {
         Ok(ok) => ok,
@@ -118,7 +119,7 @@ impl Pal for Sys {
         Ok(())
     }
 
-    unsafe fn brk(addr: *mut c_void) -> *mut c_void {
+    unsafe fn brk(addr: *mut c_void) -> Result<*mut c_void> {
         // On first invocation, allocate a buffer for brk
         if BRK_CUR.is_null() {
             // 4 megabytes of RAM ought to be enough for anybody
@@ -131,12 +132,7 @@ impl Pal for Sys {
                 MAP_ANONYMOUS,
                 0,
                 0,
-            );
-            if allocated == !0 as *mut c_void
-            /* MAP_FAILED */
-            {
-                return !0 as *mut c_void;
-            }
+            )?;
 
             BRK_CUR = allocated;
             BRK_END = (allocated as *mut u8).add(BRK_MAX_SIZE) as *mut c_void;
@@ -144,15 +140,14 @@ impl Pal for Sys {
 
         if addr.is_null() {
             // Lookup what previous brk() invocations have set the address to
-            BRK_CUR
+            Ok(BRK_CUR)
         } else if BRK_CUR <= addr && addr < BRK_END {
             // It's inside buffer, return
             BRK_CUR = addr;
-            addr
+            Ok(addr)
         } else {
             // It was outside of valid range
-            ERRNO.set(ENOMEM);
-            ptr::null_mut()
+            Err(Errno(ENOMEM))
         }
     }
 
@@ -214,22 +209,28 @@ impl Pal for Sys {
         loop {}
     }
 
-    unsafe fn execve(path: CStr, argv: *const *mut c_char, envp: *const *mut c_char) -> c_int {
-        e(self::exec::execve(
+    unsafe fn execve(path: CStr, argv: *const *mut c_char, envp: *const *mut c_char) -> Result<()> {
+        self::exec::execve(
             Executable::AtPath(path),
             self::exec::ArgEnv::C { argv, envp },
             None,
-        )) as c_int
+        )?;
+        unreachable!()
     }
-    unsafe fn fexecve(fildes: c_int, argv: *const *mut c_char, envp: *const *mut c_char) -> c_int {
-        e(self::exec::execve(
+    unsafe fn fexecve(
+        fildes: c_int,
+        argv: *const *mut c_char,
+        envp: *const *mut c_char,
+    ) -> Result<()> {
+        self::exec::execve(
             Executable::InFd {
                 file: File::new(fildes),
                 arg0: CStr::from_ptr(argv.read()).to_bytes(),
             },
             self::exec::ArgEnv::C { argv, envp },
             None,
-        )) as c_int
+        )?;
+        unreachable!()
     }
 
     fn fchdir(fd: c_int) -> Result<()> {
@@ -251,8 +252,8 @@ impl Pal for Sys {
         Ok(())
     }
 
-    fn fcntl(fd: c_int, cmd: c_int, args: c_ulonglong) -> c_int {
-        e(syscall::fcntl(fd as usize, cmd as usize, args as usize)) as c_int
+    fn fcntl(fd: c_int, cmd: c_int, args: c_ulonglong) -> Result<c_int> {
+        Ok(syscall::fcntl(fd as usize, cmd as usize, args as usize)? as c_int)
     }
 
     fn fdatasync(fd: c_int) -> Result<()> {
@@ -261,25 +262,26 @@ impl Pal for Sys {
         Ok(())
     }
 
-    fn flock(_fd: c_int, _operation: c_int) -> c_int {
+    fn flock(_fd: c_int, _operation: c_int) -> Result<()> {
         // TODO: Redox does not have file locking yet
-        0
+        Ok(())
     }
 
-    fn fork() -> pid_t {
+    unsafe fn fork() -> Result<pid_t> {
+        // TODO: Find way to avoid lock.
         let _guard = clone::wrlock();
-        let res = clone::fork_impl();
-        e(res) as pid_t
+
+        Ok(clone::fork_impl()? as pid_t)
     }
 
-    // FIXME: unsound
-    fn fstat(fildes: c_int, buf: *mut stat) -> c_int {
-        unsafe { e(libredox::fstat(fildes as usize, buf).map(|()| 0)) as c_int }
+    unsafe fn fstat(fildes: c_int, buf: *mut stat) -> Result<()> {
+        libredox::fstat(fildes as usize, buf)?;
+        Ok(())
     }
 
-    // FIXME: unsound
-    fn fstatvfs(fildes: c_int, buf: *mut statvfs) -> c_int {
-        unsafe { e(libredox::fstatvfs(fildes as usize, buf).map(|()| 0)) as c_int }
+    unsafe fn fstatvfs(fildes: c_int, buf: *mut statvfs) -> Result<()> {
+        libredox::fstatvfs(fildes as usize, buf)?;
+        Ok(())
     }
 
     fn fsync(fd: c_int) -> Result<()> {
@@ -306,35 +308,26 @@ impl Pal for Sys {
         Ok(redox_rt::sys::sys_futex_wake(addr, num)?)
     }
 
-    // FIXME: unsound
-    fn futimens(fd: c_int, times: *const timespec) -> c_int {
-        unsafe { e(libredox::futimens(fd as usize, times).map(|()| 0)) as c_int }
+    unsafe fn futimens(fd: c_int, times: *const timespec) -> Result<()> {
+        libredox::futimens(fd as usize, times)?;
+        Ok(())
     }
 
-    // FIXME: unsound
-    fn utimens(path: CStr, times: *const timespec) -> c_int {
-        match File::open(path, fcntl::O_PATH | fcntl::O_CLOEXEC) {
-            Ok(file) => Self::futimens(*file, times),
-            Err(_) => -1,
-        }
+    unsafe fn utimens(path: CStr, times: *const timespec) -> Result<()> {
+        let file = File::open(path, fcntl::O_PATH | fcntl::O_CLOEXEC)?;
+        Self::futimens(*file, times)
     }
 
-    // FIXME: unsound
-    fn getcwd(buf: *mut c_char, size: size_t) -> *mut c_char {
+    unsafe fn getcwd(buf: *mut c_char, size: size_t) -> Result<()> {
         // TODO: Not using MaybeUninit seems a little unsafe
 
         let buf_slice = unsafe { slice::from_raw_parts_mut(buf as *mut u8, size as usize) };
         if buf_slice.is_empty() {
-            ERRNO.set(EINVAL);
-            return ptr::null_mut();
-        }
-
-        if path::getcwd(buf_slice).is_none() {
-            ERRNO.set(ERANGE);
-            return ptr::null_mut();
+            return Err(Errno(EINVAL));
         }
 
-        buf
+        path::getcwd(buf_slice).ok_or(Errno(ERANGE))?;
+        Ok(())
     }
 
     fn getdents(fd: c_int, buf: &mut [u8], opaque: u64) -> Result<usize> {
@@ -414,30 +407,29 @@ impl Pal for Sys {
     }
 
     fn getegid() -> gid_t {
-        e(syscall::getegid()) as gid_t
+        syscall::getegid().unwrap() as gid_t
     }
 
     fn geteuid() -> uid_t {
-        e(syscall::geteuid()) as uid_t
+        syscall::geteuid().unwrap() as uid_t
     }
 
     fn getgid() -> gid_t {
-        e(syscall::getgid()) as gid_t
+        syscall::getgid().unwrap() as gid_t
     }
 
-    unsafe fn getgroups(size: c_int, list: *mut gid_t) -> c_int {
+    unsafe fn getgroups(size: c_int, list: *mut gid_t) -> Result<c_int> {
         // TODO
         eprintln!("relibc getgroups({}, {:p}): not implemented", size, list);
-        ERRNO.set(ENOSYS);
-        -1
+        Err(Errno(ENOSYS))
     }
 
     fn getpagesize() -> usize {
         PAGE_SIZE
     }
 
-    fn getpgid(pid: pid_t) -> pid_t {
-        e(syscall::getpgid(pid as usize)) as pid_t
+    fn getpgid(pid: pid_t) -> Result<pid_t> {
+        Ok(syscall::getpgid(pid as usize)? as pid_t)
     }
 
     fn getpid() -> pid_t {
@@ -445,19 +437,16 @@ impl Pal for Sys {
     }
 
     fn getppid() -> pid_t {
-        e(syscall::getppid()) as pid_t
+        syscall::getppid().unwrap() as pid_t
     }
 
-    fn getpriority(which: c_int, who: id_t) -> c_int {
+    fn getpriority(which: c_int, who: id_t) -> Result<c_int> {
         // TODO
         eprintln!("getpriority({}, {}): not implemented", which, who);
-        ERRNO.set(ENOSYS);
-        -1
+        Err(Errno(ENOSYS))
     }
 
-    fn getrandom(buf: &mut [u8], flags: c_uint) -> ssize_t {
-        //TODO: make this a system call?
-
+    fn getrandom(buf: &mut [u8], flags: c_uint) -> Result<usize> {
         let path = if flags & sys_random::GRND_RANDOM != 0 {
             //TODO: /dev/random equivalent
             "/scheme/rand"
@@ -470,16 +459,9 @@ impl Pal for Sys {
             open_flags |= syscall::O_NONBLOCK;
         }
 
-        let fd = e(syscall::open(path, open_flags));
-        if fd == !0 {
-            return -1;
-        }
-
-        let res = e(syscall::read(fd, buf)) as ssize_t;
-
-        let _ = syscall::close(fd);
-
-        res
+        //TODO: store fd internally
+        let fd = FdGuard::new(syscall::open(path, open_flags)?);
+        Ok(syscall::read(*fd, buf)?)
     }
 
     unsafe fn getrlimit(resource: c_int, rlim: *mut rlimit) -> Result<()> {
@@ -504,13 +486,13 @@ impl Pal for Sys {
         Err(Errno(EPERM))
     }
 
-    fn getrusage(who: c_int, r_usage: &mut rusage) -> c_int {
+    fn getrusage(who: c_int, r_usage: &mut rusage) -> Result<()> {
         //TODO
         eprintln!("relibc getrusage({}, {:p}): not implemented", who, r_usage);
-        0
+        Ok(())
     }
 
-    fn getsid(pid: pid_t) -> pid_t {
+    fn getsid(pid: pid_t) -> Result<pid_t> {
         let mut buf = [0; mem::size_of::<usize>()];
         let path = if pid == 0 {
             format!("/scheme/thisproc/current/session_id")
@@ -518,29 +500,21 @@ impl Pal for Sys {
             format!("/scheme/proc/{}/session_id", pid)
         };
         let path_c = CString::new(path).unwrap();
-        match File::open(CStr::borrow(&path_c), fcntl::O_RDONLY | fcntl::O_CLOEXEC) {
-            Ok(mut file) => match file.read(&mut buf) {
-                Ok(_) => usize::from_ne_bytes(buf).try_into().unwrap(),
-                Err(_) => -1,
-            },
-            Err(_) => -1,
-        }
+        let mut file = File::open(CStr::borrow(&path_c), fcntl::O_RDONLY | fcntl::O_CLOEXEC)?;
+        file.read(&mut buf)
+            .map_err(|err| Errno(err.raw_os_error().unwrap_or(EIO)))?;
+        Ok(usize::from_ne_bytes(buf).try_into().unwrap())
     }
 
     fn gettid() -> pid_t {
-        //TODO
+        // TODO: TIDs do not exist on Redox, at least in a form where they can be sent to other
+        // processes and used in various syscalls from there. Should the fd be returned here?
         Self::getpid()
     }
 
-    fn gettimeofday(tp: *mut timeval, tzp: *mut timezone) -> c_int {
+    unsafe fn gettimeofday(tp: *mut timeval, tzp: *mut timezone) -> Result<()> {
         let mut redox_tp = redox_timespec::default();
-        let err = e(syscall::clock_gettime(
-            syscall::CLOCK_REALTIME,
-            &mut redox_tp,
-        )) as c_int;
-        if err < 0 {
-            return err;
-        }
+        syscall::clock_gettime(syscall::CLOCK_REALTIME, &mut redox_tp)?;
         unsafe {
             (*tp).tv_sec = redox_tp.tv_sec as time_t;
             (*tp).tv_usec = (redox_tp.tv_nsec / 1000) as suseconds_t;
@@ -550,11 +524,11 @@ impl Pal for Sys {
                 (*tzp).tz_dsttime = 0;
             }
         }
-        0
+        Ok(())
     }
 
     fn getuid() -> uid_t {
-        e(syscall::getuid()) as pid_t
+        syscall::getuid().unwrap() as pid_t
     }
 
     fn lchown(path: CStr, owner: uid_t, group: gid_t) -> Result<()> {
@@ -612,14 +586,14 @@ impl Pal for Sys {
         Ok(())
     }
 
-    unsafe fn mlock(addr: *const c_void, len: usize) -> c_int {
+    unsafe fn mlock(addr: *const c_void, len: usize) -> Result<()> {
         // Redox never swaps
-        0
+        Ok(())
     }
 
-    fn mlockall(flags: c_int) -> c_int {
+    unsafe fn mlockall(flags: c_int) -> Result<()> {
         // Redox never swaps
-        0
+        Ok(())
     }
 
     unsafe fn mmap(
@@ -629,7 +603,7 @@ impl Pal for Sys {
         flags: c_int,
         fildes: c_int,
         off: off_t,
-    ) -> *mut c_void {
+    ) -> Result<*mut c_void> {
         let map = Map {
             offset: off as usize,
             size: round_up_to_page_size(len),
@@ -639,11 +613,11 @@ impl Pal for Sys {
             address: addr as usize,
         };
 
-        if flags & MAP_ANONYMOUS == MAP_ANONYMOUS {
-            e(syscall::fmap(!0, &map)) as *mut c_void
+        Ok(if flags & MAP_ANONYMOUS == MAP_ANONYMOUS {
+            syscall::fmap(!0, &map)?
         } else {
-            e(syscall::fmap(fildes as usize, &map)) as *mut c_void
-        }
+            syscall::fmap(fildes as usize, &map)?
+        } as *mut c_void)
     }
 
     unsafe fn mremap(
@@ -652,60 +626,59 @@ impl Pal for Sys {
         new_len: usize,
         flags: c_int,
         args: *mut c_void,
-    ) -> *mut c_void {
-        MAP_FAILED
+    ) -> Result<*mut c_void> {
+        Err(Errno(ENOSYS))
     }
 
-    unsafe fn mprotect(addr: *mut c_void, len: usize, prot: c_int) -> c_int {
-        e(syscall::mprotect(
+    unsafe fn mprotect(addr: *mut c_void, len: usize, prot: c_int) -> Result<()> {
+        syscall::mprotect(
             addr as usize,
             round_up_to_page_size(len),
             syscall::MapFlags::from_bits((prot as usize) << 16)
                 .expect("mprotect: invalid bit pattern"),
-        )) as c_int
+        )?;
+        Ok(())
     }
 
-    unsafe fn msync(addr: *mut c_void, len: usize, flags: c_int) -> c_int {
+    unsafe fn msync(addr: *mut c_void, len: usize, flags: c_int) -> Result<()> {
         eprintln!(
             "relibc msync({:p}, 0x{:x}, 0x{:x}): not implemented",
             addr, len, flags
         );
-        e(Err(syscall::Error::new(syscall::ENOSYS))) as c_int
+        Err(Errno(ENOSYS))
         /* TODO
-        e(syscall::msync(
+        syscall::msync(
             addr as usize,
             round_up_to_page_size(len),
             flags
-        )) as c_int
+        )?;
         */
     }
 
-    unsafe fn munlock(addr: *const c_void, len: usize) -> c_int {
+    unsafe fn munlock(addr: *const c_void, len: usize) -> Result<()> {
         // Redox never swaps
-        0
+        Ok(())
     }
 
-    fn munlockall() -> c_int {
+    unsafe fn munlockall() -> Result<()> {
         // Redox never swaps
-        0
+        Ok(())
     }
 
-    unsafe fn munmap(addr: *mut c_void, len: usize) -> c_int {
-        if e(syscall::funmap(addr as usize, round_up_to_page_size(len))) == !0 {
-            return !0;
-        }
-        0
+    unsafe fn munmap(addr: *mut c_void, len: usize) -> Result<()> {
+        syscall::funmap(addr as usize, round_up_to_page_size(len))?;
+        Ok(())
     }
 
-    unsafe fn madvise(addr: *mut c_void, len: usize, flags: c_int) -> c_int {
+    unsafe fn madvise(addr: *mut c_void, len: usize, flags: c_int) -> Result<()> {
         eprintln!(
             "relibc madvise({:p}, 0x{:x}, 0x{:x}): not implemented",
             addr, len, flags
         );
-        e(Err(syscall::Error::new(syscall::ENOSYS))) as c_int
+        Err(Errno(ENOSYS))
     }
 
-    fn nanosleep(rqtp: *const timespec, rmtp: *mut timespec) -> c_int {
+    unsafe fn nanosleep(rqtp: *const timespec, rmtp: *mut timespec) -> Result<()> {
         let redox_rqtp = unsafe { redox_timespec::from(&*rqtp) };
         let mut redox_rmtp: redox_timespec;
         if rmtp.is_null() {
@@ -713,18 +686,14 @@ impl Pal for Sys {
         } else {
             redox_rmtp = unsafe { redox_timespec::from(&*rmtp) };
         }
-        match e(syscall::nanosleep(&redox_rqtp, &mut redox_rmtp)) as c_int {
-            -1 => -1,
-            _ => {
-                unsafe {
-                    if !rmtp.is_null() {
-                        (*rmtp).tv_sec = redox_rmtp.tv_sec as time_t;
-                        (*rmtp).tv_nsec = redox_rmtp.tv_nsec as c_long;
-                    }
-                }
-                0
+        syscall::nanosleep(&redox_rqtp, &mut redox_rmtp)?;
+        unsafe {
+            if !rmtp.is_null() {
+                (*rmtp).tv_sec = redox_rmtp.tv_sec as time_t;
+                (*rmtp).tv_nsec = redox_rmtp.tv_nsec as c_long;
             }
         }
+        Ok(())
     }
 
     fn open(path: CStr, oflag: c_int, mode: mode_t) -> Result<c_int> {
@@ -766,11 +735,11 @@ impl Pal for Sys {
         }
     }
 
-    fn read(fd: c_int, buf: &mut [u8]) -> Result<ssize_t> {
+    fn read(fd: c_int, buf: &mut [u8]) -> Result<usize> {
         let fd = usize::try_from(fd).map_err(|_| Errno(EBADF))?;
-        Ok(redox_rt::sys::posix_read(fd, buf)? as ssize_t)
+        Ok(redox_rt::sys::posix_read(fd, buf)?)
     }
-    fn pread(fd: c_int, buf: &mut [u8], offset: off_t) -> Result<ssize_t> {
+    fn pread(fd: c_int, buf: &mut [u8], offset: off_t) -> Result<usize> {
         unsafe {
             Ok(syscall::syscall5(
                 syscall::SYS_READ2,
@@ -779,11 +748,11 @@ impl Pal for Sys {
                 buf.len(),
                 offset as usize,
                 !0,
-            )? as ssize_t)
+            )?)
         }
     }
 
-    fn fpath(fildes: c_int, out: &mut [u8]) -> Result<ssize_t> {
+    fn fpath(fildes: c_int, out: &mut [u8]) -> Result<usize> {
         // Since this is used by realpath, it converts from the old format to the new one for
         // compatibility reasons
         let mut buf = [0; limits::PATH_MAX];
@@ -807,12 +776,12 @@ impl Pal for Sys {
             ),
         };
         match res {
-            Ok(()) => Ok(cursor.position() as ssize_t),
+            Ok(()) => Ok(cursor.position() as usize),
             Err(_err) => Err(Errno(ENAMETOOLONG)),
         }
     }
 
-    fn readlink(pathname: CStr, out: &mut [u8]) -> Result<ssize_t> {
+    fn readlink(pathname: CStr, out: &mut [u8]) -> Result<usize> {
         let file = File::open(
             pathname,
             fcntl::O_RDONLY | fcntl::O_SYMLINK | fcntl::O_CLOEXEC,
@@ -989,7 +958,7 @@ impl Pal for Sys {
         Ok(())
     }
 
-    fn waitpid(mut pid: pid_t, stat_loc: *mut c_int, options: c_int) -> pid_t {
+    unsafe fn waitpid(mut pid: pid_t, stat_loc: *mut c_int, options: c_int) -> Result<pid_t> {
         if pid == !0 {
             pid = 0;
         }
@@ -1009,16 +978,16 @@ impl Pal for Sys {
                 let mut _event = PtraceEvent::default();
                 let _ = (&mut &session.tracer).read(&mut _event);
 
-                res = Some(e(inner(
+                res = Some(inner(
                     &mut status,
                     options | sys_wait::WNOHANG | sys_wait::WUNTRACED,
-                )));
-                if res == Some(0) {
+                ));
+                if res == Some(Ok(0)) {
                     // WNOHANG, just pretend ptrace SIGSTOP:ped this
                     status = (syscall::SIGSTOP << 8) | 0x7f;
                     assert!(syscall::wifstopped(status));
                     assert_eq!(syscall::wstopsig(status), syscall::SIGSTOP);
-                    res = Some(pid as usize);
+                    res = Some(Ok(pid as usize));
                 }
             }
         }
@@ -1028,7 +997,7 @@ impl Pal for Sys {
         // it if (and only if) a ptrace traceme was activated during
         // the wait.
         let res = res.unwrap_or_else(|| loop {
-            let res = e(inner(&mut status, options | sys_wait::WUNTRACED));
+            let res = inner(&mut status, options | sys_wait::WUNTRACED);
 
             // TODO: Also handle special PIDs here
             if !syscall::wifstopped(status)
@@ -1045,14 +1014,14 @@ impl Pal for Sys {
                 *stat_loc = status as c_int;
             }
         }
-        res as pid_t
+        Ok(res? as pid_t)
     }
 
-    fn write(fd: c_int, buf: &[u8]) -> Result<ssize_t> {
+    fn write(fd: c_int, buf: &[u8]) -> Result<usize> {
         let fd = usize::try_from(fd).map_err(|_| Errno(EBADFD))?;
-        Ok(redox_rt::sys::posix_write(fd, buf)? as ssize_t)
+        Ok(redox_rt::sys::posix_write(fd, buf)?)
     }
-    fn pwrite(fd: c_int, buf: &[u8], offset: off_t) -> Result<ssize_t> {
+    fn pwrite(fd: c_int, buf: &[u8], offset: off_t) -> Result<usize> {
         unsafe {
             Ok(syscall::syscall5(
                 syscall::SYS_WRITE2,
@@ -1061,7 +1030,7 @@ impl Pal for Sys {
                 buf.len(),
                 offset as usize,
                 !0,
-            )? as ssize_t)
+            )?)
         }
     }
 
diff --git a/src/platform/redox/signal.rs b/src/platform/redox/signal.rs
index 0ae511bbec63407e17a7f85a5f4bc7e657955cac..e8104b18678c70f8a868c88174194b9c7890f67c 100644
--- a/src/platform/redox/signal.rs
+++ b/src/platform/redox/signal.rs
@@ -1,15 +1,9 @@
-use core::mem::{self, offset_of};
-use redox_rt::signal::{
-    PosixStackt, SigStack, Sigaction, SigactionFlags, SigactionKind, Sigaltstack, SignalHandler,
-};
-use syscall::{self, Result};
-
 use super::{
     super::{types::*, Pal, PalSignal},
     e, Sys,
 };
 use crate::{
-    error::Errno,
+    error::{Errno, Result},
     header::{
         errno::{EINVAL, ENOSYS},
         signal::{
@@ -21,6 +15,13 @@ use crate::{
     },
     platform::ERRNO,
 };
+use core::mem::{self, offset_of};
+use redox_rt::{
+    proc::FdGuard,
+    signal::{
+        PosixStackt, SigStack, Sigaction, SigactionFlags, SigactionKind, Sigaltstack, SignalHandler,
+    },
+};
 
 const _: () = {
     #[track_caller]
@@ -45,41 +46,30 @@ const _: () = {
 };
 
 impl PalSignal for Sys {
-    unsafe fn getitimer(which: c_int, out: *mut itimerval) -> c_int {
+    unsafe fn getitimer(which: c_int, out: *mut itimerval) -> Result<()> {
         let path = match which {
             ITIMER_REAL => "/scheme/itimer/1",
-            _ => {
-                ERRNO.set(EINVAL);
-                return -1;
-            }
+            _ => return Err(Errno(EINVAL)),
         };
 
-        let fd = e(syscall::open(path, syscall::O_RDONLY | syscall::O_CLOEXEC));
-        if fd == !0 {
-            return -1;
-        }
+        let fd = FdGuard::new(syscall::open(path, syscall::O_RDONLY | syscall::O_CLOEXEC)?);
 
         let mut spec = syscall::ITimerSpec::default();
-        let count = e(syscall::read(fd, &mut spec));
-
-        let _ = syscall::close(fd);
-
-        if count == !0 {
-            return -1;
-        }
+        let count = syscall::read(*fd, &mut spec)?;
 
         (*out).it_interval.tv_sec = spec.it_interval.tv_sec as time_t;
         (*out).it_interval.tv_usec = spec.it_interval.tv_nsec / 1000;
         (*out).it_value.tv_sec = spec.it_value.tv_sec as time_t;
         (*out).it_value.tv_usec = spec.it_value.tv_nsec / 1000;
 
-        0
+        Ok(())
     }
 
-    fn kill(pid: pid_t, sig: c_int) -> c_int {
-        e(redox_rt::sys::posix_kill(pid as usize, sig as usize).map(|()| 0)) as c_int
+    fn kill(pid: pid_t, sig: c_int) -> Result<()> {
+        redox_rt::sys::posix_kill(pid as usize, sig as usize)?;
+        Ok(())
     }
-    fn sigqueue(pid: pid_t, sig: c_int, val: sigval) -> Result<(), Errno> {
+    fn sigqueue(pid: pid_t, sig: c_int, val: sigval) -> Result<()> {
         Ok(redox_rt::sys::posix_sigqueue(
             pid as usize,
             sig as usize,
@@ -87,58 +77,44 @@ impl PalSignal for Sys {
         )?)
     }
 
-    fn killpg(pgrp: pid_t, sig: c_int) -> c_int {
-        e(redox_rt::sys::posix_killpg(pgrp as usize, sig as usize).map(|()| 0)) as c_int
+    fn killpg(pgrp: pid_t, sig: c_int) -> Result<()> {
+        redox_rt::sys::posix_killpg(pgrp as usize, sig as usize)?;
+        Ok(())
     }
 
-    fn raise(sig: c_int) -> Result<(), Errno> {
+    fn raise(sig: c_int) -> Result<()> {
         // TODO: Bypass kernel?
         unsafe { Self::rlct_kill(Self::current_os_tid(), sig as _) }
     }
 
-    unsafe fn setitimer(which: c_int, new: *const itimerval, old: *mut itimerval) -> c_int {
+    unsafe fn setitimer(which: c_int, new: *const itimerval, old: *mut itimerval) -> Result<()> {
         let path = match which {
             ITIMER_REAL => "/scheme/itimer/1",
-            _ => {
-                ERRNO.set(EINVAL);
-                return -1;
-            }
+            _ => return Err(Errno(EINVAL)),
         };
 
-        let fd = e(syscall::open(path, syscall::O_RDWR | syscall::O_CLOEXEC));
-        if fd == !0 {
-            return -1;
-        }
+        let fd = FdGuard::new(syscall::open(path, syscall::O_RDWR | syscall::O_CLOEXEC)?);
 
         let mut spec = syscall::ITimerSpec::default();
 
-        let mut count = e(syscall::read(fd, &mut spec));
+        let _ = syscall::read(*fd, &mut spec)?;
 
-        if count != !0 {
-            unsafe {
-                if !old.is_null() {
-                    (*old).it_interval.tv_sec = spec.it_interval.tv_sec as time_t;
-                    (*old).it_interval.tv_usec = spec.it_interval.tv_nsec / 1000;
-                    (*old).it_value.tv_sec = spec.it_value.tv_sec as time_t;
-                    (*old).it_value.tv_usec = spec.it_value.tv_nsec / 1000;
-                }
-
-                spec.it_interval.tv_sec = (*new).it_interval.tv_sec as i64;
-                spec.it_interval.tv_nsec = (*new).it_interval.tv_usec * 1000;
-                spec.it_value.tv_sec = (*new).it_value.tv_sec as i64;
-                spec.it_value.tv_nsec = (*new).it_value.tv_usec * 1000;
+        unsafe {
+            if !old.is_null() {
+                (*old).it_interval.tv_sec = spec.it_interval.tv_sec as time_t;
+                (*old).it_interval.tv_usec = spec.it_interval.tv_nsec / 1000;
+                (*old).it_value.tv_sec = spec.it_value.tv_sec as time_t;
+                (*old).it_value.tv_usec = spec.it_value.tv_nsec / 1000;
             }
 
-            count = e(syscall::write(fd, &spec));
-        }
-
-        let _ = syscall::close(fd);
-
-        if count == !0 {
-            return -1;
+            spec.it_interval.tv_sec = (*new).it_interval.tv_sec as i64;
+            spec.it_interval.tv_nsec = (*new).it_interval.tv_usec * 1000;
+            spec.it_value.tv_sec = (*new).it_value.tv_sec as i64;
+            spec.it_value.tv_nsec = (*new).it_value.tv_usec * 1000;
         }
 
-        0
+        let _ = syscall::write(*fd, &spec)?;
+        Ok(())
     }
 
     fn sigaction(
diff --git a/src/platform/redox/socket.rs b/src/platform/redox/socket.rs
index 6d91c53991406ca2ff2d3db3c7c3f055e2246407..4f5448005288af4777866d1a7d3a707038cdc6ea 100644
--- a/src/platform/redox/socket.rs
+++ b/src/platform/redox/socket.rs
@@ -306,7 +306,9 @@ impl PalSocket for Sys {
             return -1;
         }
         if address == ptr::null_mut() || address_len == ptr::null_mut() {
-            Self::read(socket, slice::from_raw_parts_mut(buf as *mut u8, len)).or_minus_one_errno()
+            Self::read(socket, slice::from_raw_parts_mut(buf as *mut u8, len))
+                .map(|u| u as ssize_t)
+                .or_minus_one_errno()
         } else {
             let fd = e(syscall::dup(socket as usize, b"listen"));
             if fd == !0 {
@@ -318,6 +320,7 @@ impl PalSocket for Sys {
             }
 
             let ret = Self::read(fd as c_int, slice::from_raw_parts_mut(buf as *mut u8, len))
+                .map(|u| u as ssize_t)
                 .or_minus_one_errno();
             let _ = syscall::close(fd);
             ret
@@ -351,10 +354,13 @@ impl PalSocket for Sys {
             return -1;
         }
         if dest_addr == ptr::null() || dest_len == 0 {
-            Self::write(socket, slice::from_raw_parts(buf as *const u8, len)).or_minus_one_errno()
+            Self::write(socket, slice::from_raw_parts(buf as *const u8, len))
+                .map(|u| u as ssize_t)
+                .or_minus_one_errno()
         } else {
             let fd = bind_or_connect!(connect copy, socket, dest_addr, dest_len);
             let ret = Self::write(fd as c_int, slice::from_raw_parts(buf as *const u8, len))
+                .map(|u| u as ssize_t)
                 .or_minus_one_errno();
             let _ = syscall::close(fd);
             ret
@@ -389,7 +395,9 @@ impl PalSocket for Sys {
                 tv_nsec: timeval.tv_usec * 1000,
             };
 
-            let ret = Self::write(fd as c_int, &timespec).or_minus_one_errno();
+            let ret = Self::write(fd as c_int, &timespec)
+                .map(|u| u as ssize_t)
+                .or_minus_one_errno();
 
             let _ = syscall::close(fd);
 
diff --git a/src/platform/rlb.rs b/src/platform/rlb.rs
index ec9ed09892e1c19adb26d64694273d8177a21a6c..ade9555892b92a65f5fe498e0bb9d8a00fd06dfb 100644
--- a/src/platform/rlb.rs
+++ b/src/platform/rlb.rs
@@ -61,7 +61,9 @@ impl RawLineBuffer {
                 self.buf.set_len(capacity);
             }
 
-            let read = Sys::read(self.fd, &mut self.buf[len..]).or_minus_one_errno();
+            let read = Sys::read(self.fd, &mut self.buf[len..])
+                .map(|u| u as isize)
+                .or_minus_one_errno();
 
             let read_usize = read.max(0) as usize;