diff --git a/src/py/flwr/superexec/exec_servicer_test.py b/src/py/flwr/superexec/exec_servicer_test.py
index 41f67b74c48b..edc91df4530e 100644
--- a/src/py/flwr/superexec/exec_servicer_test.py
+++ b/src/py/flwr/superexec/exec_servicer_test.py
@@ -36,7 +36,7 @@ def test_start_run() -> None:
         run_res.proc = proc
 
     executor = MagicMock()
-    executor.start_run = lambda _: run_res
+    executor.start_run = lambda _, __: run_res
 
     context_mock = MagicMock()