diff --git a/library/core/src/task/wake.rs b/library/core/src/task/wake.rs
index 3fc97a199a6b..40f0b0c51446 100644
--- a/library/core/src/task/wake.rs
+++ b/library/core/src/task/wake.rs
@@ -787,3 +787,8 @@ impl fmt::Debug for LocalWaker {
             .finish()
     }
 }
+
+#[unstable(feature = "local_waker", issue = "118959")]
+impl !Send for LocalWaker {}
+#[unstable(feature = "local_waker", issue = "118959")]
+impl !Sync for LocalWaker {}