diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 030f4f1d12cc8..f8c8d4b02db66 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -69,7 +69,6 @@
 #![feature(allow_internal_unstable)]
 #![feature(arbitrary_self_types)]
 #![feature(asm)]
-#![feature(associated_type_defaults)]
 #![feature(bound_cloned)]
 #![feature(cfg_target_has_atomic)]
 #![feature(concat_idents)]
diff --git a/src/libcore/ops/arith.rs b/src/libcore/ops/arith.rs
index 8139305f5302d..3c009d644c64e 100644
--- a/src/libcore/ops/arith.rs
+++ b/src/libcore/ops/arith.rs
@@ -508,7 +508,7 @@ div_impl_float! { f32 f64 }
 pub trait Rem<Rhs=Self> {
     /// The resulting type after applying the `%` operator.
     #[stable(feature = "rust1", since = "1.0.0")]
-    type Output = Self;
+    type Output;
 
     /// Performs the `%` operation.
     #[must_use]