diff --git a/gnuviechadmin/hostingpackages/models.py b/gnuviechadmin/hostingpackages/models.py
index 89b7e37..20698ef 100644
--- a/gnuviechadmin/hostingpackages/models.py
+++ b/gnuviechadmin/hostingpackages/models.py
@@ -255,7 +255,7 @@ class CustomerHostingPackage(HostingPackageBase):
         ).aggregate(
             mailbox_sum=models.Sum('number')
         )
-        return self.mailboxcount + result['mailbox_sum']
+        return self.mailboxcount + (result['mailbox_sum'] or 0)
 
     def get_databases(self):
         """