diff --git a/Lib/test/test_structseq.py b/Lib/test/test_structseq.py
index 6e57e22..f01bc44 100644
--- a/Lib/test/test_structseq.py
+++ b/Lib/test/test_structseq.py
@@ -7,6 +7,7 @@
 
     def test_tuple(self):
         t = time.gmtime()
+        assert isinstance(t, tuple)
         astuple = tuple(t)
         self.assertEqual(len(t), len(astuple))
         self.assertEqual(t, astuple)