bug [ 1238170 ] threading.Thread uses {} as default argument
diff --git a/Lib/threading.py b/Lib/threading.py
index cbcc1f9..fe4490f 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -374,9 +374,11 @@
     __exc_info = _sys.exc_info
 
     def __init__(self, group=None, target=None, name=None,
-                 args=(), kwargs={}, verbose=None):
+                 args=(), kwargs=None, verbose=None):
         assert group is None, "group argument must be None for now"
         _Verbose.__init__(self, verbose)
+        if kwargs is None:
+            kwargs = {}
         self.__target = target
         self.__name = str(name or _newname())
         self.__args = args