diff --git a/tests/tasks/test_utils.py b/tests/tasks/test_utils.py
index 47a8bb5ce2..3c66e7d956 100644
--- a/tests/tasks/test_utils.py
+++ b/tests/tasks/test_utils.py
@@ -58,7 +58,6 @@ class JSONNormalizeTestCase(SimpleTestCase):
     def test_encode_error(self):
         for example in [self, any, datetime.datetime.now()]:
             with self.subTest(example):
-                self.assertFalse(utils.is_json_serializable(example))
                 self.assertRaises(TypeError, utils.json_normalize, example)