diff --git a/stock.py b/stock.py
index aad0b2ad2f..4d4baf5b24 100644
--- a/stock.py
+++ b/stock.py
@@ -140,6 +140,8 @@ class ShipmentCostMixin:
             return Currency.compute(
                 self.cost_currency_used, self.cost_used,
                 self.company.currency, round=False)
+        else:
+            return Decimal(0)
 
 
 class ShipmentOutCostMixin(ShipmentCostMixin):