diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
index c3b2a4fc72b..7cda0dced9a 100644
--- a/Lib/test/test_dis.py
+++ b/Lib/test/test_dis.py
@@ -276,7 +276,7 @@ def test_dis_traceback(self):
         old = getattr(sys, 'last_traceback', not_defined)
 
         def cleanup():
-            if old != not_defined:
+            if old is not not_defined:
                 sys.last_traceback = old
             else:
                 del sys.last_traceback