diff --git a/celery/beat.py b/celery/beat.py
index 217a9441aeb..65dd660da5a 100644
--- a/celery/beat.py
+++ b/celery/beat.py
@@ -237,7 +237,7 @@ def is_due(self, entry):
     def _when(self, entry, next_time_to_run, mktime=time.mktime):
         adjust = self.adjust
 
-        return (mktime(entry.schedule.now().timetuple()) +
+        return (mktime(entry._default_now().timetuple()) +
                 (adjust(next_time_to_run) or 0))
 
     def populate_heap(self, event_t=event_t, heapify=heapq.heapify):