diff --git a/stdlib/2and3/threading.pyi b/stdlib/2and3/threading.pyi
index 924b32996..6d0e4a69d 100644
--- a/stdlib/2and3/threading.pyi
+++ b/stdlib/2and3/threading.pyi
@@ -91,6 +91,7 @@ class Lock:
     else:
         def acquire(self, blocking: bool = ...) -> bool: ...
     def release(self) -> None: ...
+    def locked(self) -> bool: ...
 
 
 class _RLock: