diff --git a/addons/delivery/models/sale_order.py b/addons/delivery/models/sale_order.py
index a2d4f491e97..127b7fa459b 100644
--- a/addons/delivery/models/sale_order.py
+++ b/addons/delivery/models/sale_order.py
@@ -88,8 +88,7 @@ class SaleOrder(models.Model):
             }
         }
 
-    def _create_delivery_line(self, carrier, price_unit):
-        SaleOrderLine = self.env['sale.order.line']
+    def _prepare_delivery_line_vals(self, carrier, price_unit):
         context = {}
         if self.partner_id:
             # set delivery detail in the customer language
@@ -123,9 +122,12 @@ class SaleOrder(models.Model):
             values['name'] += '\n' + _('Free Shipping')
         if self.order_line:
             values['sequence'] = self.order_line[-1].sequence + 1
-        sol = SaleOrderLine.sudo().create(values)
         del context
-        return sol
+        return values
+
+    def _create_delivery_line(self, carrier, price_unit):
+        values = self._prepare_delivery_line_vals(carrier, price_unit)
+        return self.env['sale.order.line'].sudo().create(values)
 
     @api.depends('order_line.is_delivery', 'order_line.is_downpayment')
     def _compute_invoice_status(self):
diff --git a/addons/stock_delivery/models/stock_picking.py b/addons/stock_delivery/models/stock_picking.py
index 5de885181fc..9c6412d4f3f 100644
--- a/addons/stock_delivery/models/stock_picking.py
+++ b/addons/stock_delivery/models/stock_picking.py
@@ -200,18 +200,29 @@ class StockPicking(models.Model):
         self.ensure_one()
         self.carrier_id.get_return_label(self)
 
+    def _get_matching_delivery_lines(self):
+        return self.sale_id.order_line.filtered(
+            lambda l: l.is_delivery
+            and l.currency_id.is_zero(l.price_unit)
+            and l.product_id == self.carrier_id.product_id
+        )
+
+    def _prepare_sale_delivery_line_vals(self):
+        return {
+            'price_unit': self.carrier_price,
+            # remove the estimated price from the description
+            'name': self.carrier_id.with_context(lang=self.partner_id.lang).name,
+        }
+
     def _add_delivery_cost_to_so(self):
         self.ensure_one()
         sale_order = self.sale_id
         if sale_order and self.carrier_id.invoice_policy == 'real' and self.carrier_price:
-            delivery_lines = sale_order.order_line.filtered(lambda l: l.is_delivery and l.currency_id.is_zero(l.price_unit) and l.product_id == self.carrier_id.product_id)
+            delivery_lines = self._get_matching_delivery_lines()
             if not delivery_lines:
                 delivery_lines = sale_order._create_delivery_line(self.carrier_id, self.carrier_price)
-            delivery_lines[0].write({
-                'price_unit': self.carrier_price,
-                # remove the estimated price from the description
-                'name': self.carrier_id.with_context(lang=self.partner_id.lang).name,
-            })
+            vals = self._prepare_sale_delivery_line_vals()
+            delivery_lines[0].write(vals)
 
     def open_website_url(self):
         self.ensure_one()