diff --git a/scripts-available/CDB_Quota.sql b/scripts-available/CDB_Quota.sql
index 7971445..9d53d2a 100644
--- a/scripts-available/CDB_Quota.sql
+++ b/scripts-available/CDB_Quota.sql
@@ -33,7 +33,11 @@ BEGIN
   )
   SELECT sum(table_size*multiplier)::int8 INTO total_size FROM sizes;
 
-  RETURN total_size;
+  IF total_size IS NOT NULL THEN
+    RETURN total_size;
+  ELSE
+    RETURN 0;
+  END IF;
 END;
 $$
 LANGUAGE 'plpgsql' VOLATILE;