diff --git a/modules/product_kit/common.py b/modules/product_kit/common.py
index 687f1d5960..5b13bb92bb 100644
--- a/modules/product_kit/common.py
+++ b/modules/product_kit/common.py
@@ -437,6 +437,7 @@ def handle_shipment_exception_mixin(prefix):
 
 
 class AmendmentLineMixin:
+    __slots__ = ()
 
     def _apply_line(self, record, line):
         pool = Pool()