diff --git a/Makefile b/Makefile
index 0612c076c1b799514bd4c4b359059a4e8eeb0762..9d394c83be6d5002144392eb2008f8fd80e147a5 100644
--- a/Makefile
+++ b/Makefile
@@ -4,9 +4,9 @@ ARCH?=x86_64
 KTARGET=$(ARCH)-unknown-none
 KBUILD=build/kernel
 KRUSTC=./krustc.sh
-KRUSTCFLAGS=--target $(KTARGET).json -O -C soft-float
+KRUSTCFLAGS=--target $(KTARGET).json -C soft-float
 KCARGO=RUSTC="$(KRUSTC)" cargo
-KCARGOFLAGS=--target $(KTARGET).json -- -O -C soft-float
+KCARGOFLAGS=--target $(KTARGET).json -- -C soft-float
 
 # Userspace variables
 TARGET=$(ARCH)-unknown-redox