diff --git a/rest_framework/tests/test_serializer.py b/rest_framework/tests/test_serializer.py
index 957e3bd2b..c24976603 100644
--- a/rest_framework/tests/test_serializer.py
+++ b/rest_framework/tests/test_serializer.py
@@ -158,6 +158,7 @@ class BasicTests(TestCase):
             'email': '',
             'content': '',
             'created': None,
+            'sub_comment': ''
         }
         self.assertEqual(serializer.data, expected)