diff --git a/counter/models.py b/counter/models.py
index 46b7ceae..aff1f2b5 100644
--- a/counter/models.py
+++ b/counter/models.py
@@ -478,7 +478,9 @@ class Selling(models.Model):
         return user.is_owner(self.counter) and self.payment_method != "CARD"
 
     def can_be_viewed_by(self, user):
-        if not hasattr(self, "customer"):  # Customer can be set to Null
+        if (
+            not hasattr(self, "customer") or self.customer is None
+        ):  # Customer can be set to Null
             return False
         return user == self.customer.user