diff --git a/artiq/master/scheduler.py b/artiq/master/scheduler.py
index 1a18c0720..bc264964e 100644
--- a/artiq/master/scheduler.py
+++ b/artiq/master/scheduler.py
@@ -443,7 +443,7 @@ class Scheduler:
                                 self._worker_handlers, self.notifier,
                                 self._experiment_db, self._log_submissions)
             self._pipelines[pipeline_name] = pipeline
-            pipeline.start(self._loop)
+            pipeline.start(loop=self._loop)
         return pipeline.pool.submit(expid, priority, due_date, flush, pipeline_name)
 
     def delete(self, rid):