diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index 3eb828810909..d203f80e5e83 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -248,7 +248,6 @@
 #![feature(link_args)]
 #![feature(linkage)]
 #![feature(macro_reexport)]
-#![cfg_attr(test, feature(map_values_mut))]
 #![feature(needs_panic_runtime)]
 #![feature(num_bits_bytes)]
 #![feature(old_wrapping)]