diff --git a/osinaweb/osinacore/tasks.py b/osinaweb/osinacore/tasks.py
index 91bd66c6..394abb66 100644
--- a/osinaweb/osinacore/tasks.py
+++ b/osinaweb/osinacore/tasks.py
@@ -10,7 +10,7 @@ def set_offline():
     for staff_profile in all_staff_profiles:
         last_working_point_activity = PointActivity.objects.filter(
             point__status='Working On',
-            point__task__assigned_to=staff_profile.user,
+            point__task__assigned_to=staff_profile,
         ).order_by('-end_time').first()
 
         if last_working_point_activity and last_working_point_activity.end_time <= datetime.now() - timedelta(minutes=10):