diff --git a/shiftregister/app/models.py b/shiftregister/app/models.py
index 73e4eef..a652d27 100644
--- a/shiftregister/app/models.py
+++ b/shiftregister/app/models.py
@@ -77,7 +77,7 @@ class ShiftRegistration(models.Model):
 
     def can_cancel(self):
         return self.shift.start_at > (
-            timezone.now() + global_preferences["helper__min_cancel_time"],
+            timezone.now() + global_preferences_registry.manager()["helper__min_cancel_time"]
         )
 
     def send_reminder(self):