diff --git a/.cargo/config b/.cargo/config
index 3b89a87..2109ab5 100644
--- a/.cargo/config
+++ b/.cargo/config
@@ -3,7 +3,7 @@ rustflags = [
   "-C", "link-arg=-Tlink.x",
   "-C", "target-feature=a9,armv7-a,neon",
   "-C", "target-cpu=cortex-a9",
-  "-Zcrate-attr=feature(const_fn)"
+  #"-Zcrate-attr=feature(const_fn)"
 ]
 
 [build]
diff --git a/libcortex_a9/src/lib.rs b/libcortex_a9/src/lib.rs
index 467fdbf..2f341d3 100644
--- a/libcortex_a9/src/lib.rs
+++ b/libcortex_a9/src/lib.rs
@@ -1,6 +1,7 @@
 #![no_std]
 #![feature(llvm_asm, global_asm)]
 #![feature(never_type)]
+#![feature(const_fn)]
 
 extern crate alloc;