diff --git a/django/contrib/humanize/tests.py b/django/contrib/humanize/tests.py
index d2bb4c034e5..0f31beb81fa 100644
--- a/django/contrib/humanize/tests.py
+++ b/django/contrib/humanize/tests.py
@@ -28,7 +28,7 @@ now = datetime.datetime(2012, 3, 9, 22, 30)
 
 class MockDateTime(datetime.datetime):
     @classmethod
-    def now(self, tz=None):
+    def now(cls, tz=None):
         if tz is None or tz.utcoffset(now) is None:
             return now
         else: