diff --git a/tests/testutil.py b/tests/testutil.py
index b50ee4e507f0bfc1bcfcfffc58ef23e437bbf966..956a4788adfbc4016a5fa30c4f3de8a6a00290c8 100644
--- a/tests/testutil.py
+++ b/tests/testutil.py
@@ -218,7 +218,7 @@ class RTClient:
         try:
             att_seq = iter(self.TICKET_DATA[str(ticket_id)])
         except KeyError:
-            None
+            return None
         att_id = str(attachment_id)
         multipart_id = None
         for attch in att_seq: