diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index a9c3616..e06cd61 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -599,6 +599,10 @@
                       version.serial << 0)
         self.assertEqual(sys.implementation.hexversion, hexversion)
 
+        # PEP 421 requires that .name be lower case.
+        self.assertEqual(sys.implementation.name, 
+                         sys.implementation.name.lower())
+
 
 class SizeofTest(unittest.TestCase):