diff --git a/Lib/unittest.py b/Lib/unittest.py
index b5c6befe90d..b5a1a4b8b50 100644
--- a/Lib/unittest.py
+++ b/Lib/unittest.py
@@ -160,7 +160,7 @@ class TestResult:
         return ''.join(traceback.format_exception(exctype, value, tb))
 
     def _is_relevant_tb_level(self, tb):
-        return tb.tb_frame.f_globals.has_key('__unittest')
+        return '__unittest' in tb.tb_frame.f_globals
 
     def _count_relevant_tb_levels(self, tb):
         length = 0