diff --git a/test/dates_test.py b/test/dates_test.py
index 0df1c6e4a20070a47c6bddd6d7403dedfe0448ba..f3b1a86d830936dd542315d9017b08c76be80e1b 100644
--- a/test/dates_test.py
+++ b/test/dates_test.py
@@ -19,9 +19,9 @@ class DatesTest(ScenesTestBase):
         # Index test
         idx = Index([])
         dummy_bbox = BoundingBox(0, 0, 0, 0)
-        _ = idx.find(dummy_bbox, date_min="datestr1")
-        _ = idx.find(dummy_bbox, date_min="datestr2")
-        _ = idx.find(dummy_bbox, date_min="datestr3")
+        _ = idx.find(dummy_bbox, date_min=datestr1)
+        _ = idx.find(dummy_bbox, date_min=datestr2)
+        _ = idx.find(dummy_bbox, date_min=datestr3)
 
 
 if __name__ == '__main__':