diff --git a/swh/scheduler/celery_backend/listener.py b/swh/scheduler/celery_backend/listener.py
--- a/swh/scheduler/celery_backend/listener.py
+++ b/swh/scheduler/celery_backend/listener.py
@@ -107,8 +107,8 @@
         try_perform_actions()
 
     def task_started(event, message):
-        logger.debug('task_started: %s %s %s', event['type'],
-                     event.get('name', 'N/A'))
+        logger.debug('task_started: %s %s',
+                     event['type'], event.get('name', 'N/A'))
 
         queue_action({
             'action': 'start_task_run',