diff --git a/sale.py b/sale.py
index fc2870d..9f6ffe2 100644
--- a/sale.py
+++ b/sale.py
@@ -204,8 +204,9 @@ class Sale(metaclass=PoolMeta):
                         state_agended='no_agenda',
                         propietary=sale.party,
                         propietary_address=sale.shipment_address,
-                        contract_origin=sale.contract_ref
-                        if sale.contract_ref else None,
+                        contract_origin=(
+                            sale.contract_ref.id
+                            if sale.contract_ref else None),
                         sale_origin=sale,
                         sale_date=sale.sale_date,
                         state="draft"