diff --git a/src/header/sys_ioctl/redox.rs b/src/header/sys_ioctl/redox.rs
index c234d0d80e05118f28e1500d944becf4afebc349..3661fed41292ffe77d1a0d23caf7526086d4b973 100644
--- a/src/header/sys_ioctl/redox.rs
+++ b/src/header/sys_ioctl/redox.rs
@@ -8,6 +8,7 @@ use crate::{
 
 use super::winsize;
 
+pub const FIONREAD: c_ulong = 0x541B;
 pub const FIONBIO: c_ulong = 0x5421;
 
 pub const TCGETS: c_ulong = 0x5401;