diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 7c7e0af..745e4ad 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -119,6 +119,10 @@
         self.assertRaises(TypeError, sys.exit, 42, 42)
 
         # call without argument
+        with self.assertRaises(SystemExit) as cm:
+            sys.exit()
+        self.assertIsNone(cm.exception.code)
+
         rc, out, err = assert_python_ok('-c', 'import sys; sys.exit()')
         self.assertEqual(rc, 0)
         self.assertEqual(out, b'')