diff --git a/Lib/test/test_tcl.py b/Lib/test/test_tcl.py
index fa170ef..26e294c 100644
--- a/Lib/test/test_tcl.py
+++ b/Lib/test/test_tcl.py
@@ -2,10 +2,19 @@
 
 import unittest
 import os
+import _tkinter
 from test import test_support
 from Tkinter import Tcl
 from _tkinter import TclError
 
+
+class TkinterTest(unittest.TestCase):
+
+    def testFlattenLen(self):
+        # flatten(<object with no length>)
+        self.assertRaises(TypeError, _tkinter._flatten, True)
+
+
 class TclTest(unittest.TestCase):
 
     def setUp(self):
@@ -151,7 +160,7 @@
                 os.environ['DISPLAY'] = old_display
 
 def test_main():
-    test_support.run_unittest(TclTest)
+    test_support.run_unittest(TclTest, TkinterTest)
 
 if __name__ == "__main__":
     test_main()