diff --git a/src/lib.rs b/src/lib.rs
index 8851fbb..313e815 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,4 @@
+#![cfg(target_os = "redox")]
 #![feature(asm)]
 #![feature(const_fn)]
 #![no_std]