diff --git a/addons/purchase_stock/models/purchase.py b/addons/purchase_stock/models/purchase.py
index b4d63b36c65..557d32f3fa3 100644
--- a/addons/purchase_stock/models/purchase.py
+++ b/addons/purchase_stock/models/purchase.py
@@ -413,18 +413,17 @@ class PurchaseOrderLine(models.Model):
 
     def _get_stock_move_price_unit(self):
         self.ensure_one()
-        line = self[0]
-        order = line.order_id
-        price_unit = line.price_unit
+        order = self.order_id
+        price_unit = self.price_unit
         price_unit_prec = self.env['decimal.precision'].precision_get('Product Price')
-        if line.taxes_id:
-            qty = line.product_qty or 1
-            price_unit = line.taxes_id.with_context(round=False).compute_all(
-                price_unit, currency=line.order_id.currency_id, quantity=qty, product=line.product_id, partner=line.order_id.partner_id
+        if self.taxes_id:
+            qty = self.product_qty or 1
+            price_unit = self.taxes_id.with_context(round=False).compute_all(
+                price_unit, currency=self.order_id.currency_id, quantity=qty, product=self.product_id, partner=self.order_id.partner_id
             )['total_void']
             price_unit = float_round(price_unit / qty, precision_digits=price_unit_prec)
-        if line.product_uom.id != line.product_id.uom_id.id:
-            price_unit *= line.product_uom.factor / line.product_id.uom_id.factor
+        if self.product_uom.id != self.product_id.uom_id.id:
+            price_unit *= self.product_uom.factor / self.product_id.uom_id.factor
         if order.currency_id != order.company_id.currency_id:
             price_unit = order.currency_id._convert(
                 price_unit, order.company_id.currency_id, self.company_id, self.date_order or fields.Date.today(), round=False)