diff --git a/sale.py b/sale.py
index bd47ad56aa..8ac7688b04 100644
--- a/sale.py
+++ b/sale.py
@@ -166,7 +166,8 @@ class SaleShipmentCost(metaclass=PoolMeta):
                     raise BadRequest()
             else:
                 carrier = None
-            self.carrier = carrier
+            # Use id to get proper context
+            self.carrier = carrier.id if carrier else None
 
 
 class Line(TaxableMixin, metaclass=PoolMeta):