diff --git a/helpers/models.py b/helpers/models.py
index 6ab4a28..a5b083b 100644
--- a/helpers/models.py
+++ b/helpers/models.py
@@ -32,6 +32,6 @@ USchema = marshmallow_dataclass.class_schema(User)
 class UserSchema(USchema):
 
     def load(self, entity, *args, **kwargs):
-        if entity.get('next_daily_notify_time', None):
+        if entity.get('next_daily_notify_time', None) is not None:
             entity['next_daily_notify_time'] = entity['next_daily_notify_time'].strftime("%Y-%m-%dT%H:%M:00.000+00:00")
         return super().load(entity, *args, **kwargs)