diff --git a/addons/delivery/models/sale_order.py b/addons/delivery/models/sale_order.py
index 50cebb1da75..233723ce712 100644
--- a/addons/delivery/models/sale_order.py
+++ b/addons/delivery/models/sale_order.py
@@ -92,8 +92,13 @@ class SaleOrder(models.Model):
         }
         if self.order_line:
             values['sequence'] = self.order_line[-1].sequence + 1
-        so = SaleOrderLine.create(values)
-        so.product_id_change_margin()
+        sol = SaleOrderLine.create(values)
+        if hasattr(sol, 'product_id_change_margin'):
+            # if `sale_margin` module is installed, force computation of field `purchase_price`
+            # As there is not dependency between modules (nor a bridge module), this is the only
+            # place we can get the value for this field
+            sol.product_id_change_margin()
+        return sol
 
 
 class SaleOrderLine(models.Model):