diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index ba03ce4..18cd4ab 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -785,6 +785,17 @@ def test_message_none(self):
         err = self.get_report(Exception(''))
         self.assertIn('Exception\n', err)
 
+    def test_exception_modulename_not_unicode(self):
+        class X(Exception):
+            def __str__(self):
+                return "I am X"
+
+        X.__module__ = 42
+
+        err = self.get_report(X())
+        exp = f'<unknown>.{X.__qualname__}: I am X\n'
+        self.assertEqual(exp, err)
+
     def test_syntax_error_various_offsets(self):
         for offset in range(-5, 10):
             for add in [0, 2]: