diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index cef0567..6bbc55f 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -128,7 +128,7 @@
         return True
 
 def _sentinel(*args, **kwargs):
-    raise AssertionError('Should never called')
+    raise AssertionError('Should never be called')
 
 class TestCase(object):
     """A class whose instances are single test cases.