diff --git a/src/libcore/marker.rs b/src/libcore/marker.rs
index 27d8af2e8a88f..f6baf23b564b0 100644
--- a/src/libcore/marker.rs
+++ b/src/libcore/marker.rs
@@ -18,6 +18,7 @@
 
 use clone::Clone;
 use cmp;
+use default::Default;
 use option::Option;
 use hash::Hash;
 use hash::Hasher;
@@ -256,6 +257,12 @@ macro_rules! impls{
                 $t
             }
         }
+
+        impl<T:?Sized> Default for $t<T> {
+            fn default() -> $t<T> {
+                $t
+            }
+        }
         )
 }