diff --git a/django/test/testcases.py b/django/test/testcases.py
index 260b060c45a..1d52fed69f8 100644
--- a/django/test/testcases.py
+++ b/django/test/testcases.py
@@ -867,7 +867,9 @@ class QuietWSGIRequestHandler(WSGIRequestHandler):
         pass
 
 
-if sys.version_info >= (2, 7, 0):
+if sys.version_info >= (3, 3, 0):
+    _ImprovedEvent = threading.Event
+elif sys.version_info >= (2, 7, 0):
     _ImprovedEvent = threading._Event
 else:
     class _ImprovedEvent(threading._Event):