diff --git a/tests/mock_vws/fixtures/prepared_requests.py b/tests/mock_vws/fixtures/prepared_requests.py
index 52dd0880f..b800ed39b 100644
--- a/tests/mock_vws/fixtures/prepared_requests.py
+++ b/tests/mock_vws/fixtures/prepared_requests.py
@@ -23,7 +23,7 @@
 
 
 @RETRY_ON_TOO_MANY_REQUESTS
-def _wait_for_target_processed(vws_client: VWS, target_id: str) -> None:
+def _wait_for_target_processed(*, vws_client: VWS, target_id: str) -> None:
     """Wait for a target to be processed.
 
     We retry here because pytest-retry does not retry on exceptions