diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index 3920b57962c87..71c6a6c892eab 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -1559,7 +1559,7 @@ impl<'a> Add<&'a str> for String {
     }
 }
 
-#[stable(feature = "rust1", since = "1.12.0")]
+#[stable(feature = "stringaddassign", since = "1.12.0")]
 impl<'a> AddAssign<&'a str> for String {
     #[inline]
     fn add_assign(&mut self, other: &str) {