diff --git a/src/test/compile-fail/missing_debug_impls.rs b/src/test/compile-fail/missing_debug_impls.rs
index 4adae2f3680..5b781a40fe5 100644
--- a/src/test/compile-fail/missing_debug_impls.rs
+++ b/src/test/compile-fail/missing_debug_impls.rs
@@ -10,7 +10,8 @@
 
 // compile-flags: --crate-type lib
 #![deny(missing_debug_implementations)]
-#![allow(unused, unstable, missing_copy_implementations)]
+#![allow(unused, missing_copy_implementations)]
+#![feature(core)]
 
 use std::fmt;