diff --git a/addons/sale/models/sale_order.py b/addons/sale/models/sale_order.py
index 5e4be166c0e..6681f31bf35 100644
--- a/addons/sale/models/sale_order.py
+++ b/addons/sale/models/sale_order.py
@@ -524,25 +524,13 @@ class SaleOrder(models.Model):
 
     def update_prices(self):
         self.ensure_one()
-        lines_to_update = []
-        for line in self.order_line.filtered(lambda line: not line.display_type):
-            # TODO VFE remove price field usage
-            product = line.product_id.with_context(
-                partner=self.partner_id,
-                quantity=line.product_uom_qty,
-                date=self.date_order,
-                pricelist=self.pricelist_id.id,
-                uom=line.product_uom.id
-            )
-            price_unit = self.env['account.tax']._fix_tax_included_price_company(
-                line._get_display_price(product), line.product_id.taxes_id, line.tax_id, line.company_id)
-            if self.pricelist_id.discount_policy == 'without_discount' and price_unit:
-                price_discount_unrounded = self.pricelist_id.get_product_price(product, line.product_uom_qty, self.partner_id, self.date_order, line.product_uom.id)
-                discount = max(0, (price_unit - price_discount_unrounded) * 100 / price_unit)
-            else:
-                discount = 0
-            lines_to_update.append((1, line.id, {'price_unit': price_unit, 'discount': discount}))
-        self.update({'order_line': lines_to_update})
+        lines_to_recompute = self.order_line.filtered(lambda line: not line.display_type)
+        lines_to_recompute._compute_price_unit()
+        # Special case: we want to overwrite the existing discount on update_prices call
+        # i.e. to make sure the discount is correctly reset
+        # if pricelist discount_policy is different than when the price was first computed.
+        lines_to_recompute.discount = 0.0
+        lines_to_recompute._compute_discount()
         self.show_update_pricelist = False
         self.message_post(body=_("Product prices have been recomputed according to pricelist <b>%s<b> ", self.pricelist_id.display_name))
 
diff --git a/addons/sale/tests/test_sale_order.py b/addons/sale/tests/test_sale_order.py
index 04f09818e01..b3ab8a628b4 100644
--- a/addons/sale/tests/test_sale_order.py
+++ b/addons/sale/tests/test_sale_order.py
@@ -682,8 +682,8 @@ class TestSaleOrder(TestSaleCommon):
                 'compute_price': 'percentage'
             })
         ]
+        self.env.user.groups_id += self.env.ref('product.group_discount_per_so_line')
         pricelist.discount_policy = "without_discount"
-        self.env['product.product'].invalidate_cache(['price'])
         sale_order.update_prices()
 
         self.assertTrue(all(line.discount == 5 for line in sale_order.order_line))
@@ -691,7 +691,6 @@ class TestSaleOrder(TestSaleCommon):
         self.assertEqual(sale_order.amount_total, 0.95*so_amount)
 
         pricelist.discount_policy = "with_discount"
-        self.env['product.product'].invalidate_cache(['price'])
         sale_order.update_prices()
 
         self.assertTrue(all(line.discount == 0 for line in sale_order.order_line))