diff --git a/panoptes_client/tests/test_workflow.py b/panoptes_client/tests/test_workflow.py
index 9f52b3a..699b25c 100644
--- a/panoptes_client/tests/test_workflow.py
+++ b/panoptes_client/tests/test_workflow.py
@@ -269,7 +269,7 @@ def test_run_aggregation_with_delete_if_true(self, mock_save, mock_where, mock_f
     @patch.object(Workflow, 'get_batch_aggregations')
     def test_get_agg_property(self, mock_get_batch_aggregations):
         mock_aggregation = MagicMock()
-        setattr(mock_aggregation, 'test_property', 'returned_test_value')
+        mock_aggregation.test_property = 'returned_test_value'
 
         mock_get_batch_aggregations.return_value = iter([mock_aggregation])