diff --git a/addons/purchase/models/purchase.py b/addons/purchase/models/purchase.py
index e44f177afad..99e45f5b4b3 100644
--- a/addons/purchase/models/purchase.py
+++ b/addons/purchase/models/purchase.py
@@ -577,12 +577,7 @@ class PurchaseOrderLine(models.Model):
         if product_lang.description_purchase:
             self.name += '\n' + product_lang.description_purchase
 
-        fpos = self.order_id.fiscal_position_id
-        if self.env.uid == SUPERUSER_ID:
-            company_id = self.env.user.company_id.id
-            self.taxes_id = fpos.map_tax(self.product_id.supplier_taxes_id.filtered(lambda r: r.company_id.id == company_id))
-        else:
-            self.taxes_id = fpos.map_tax(self.product_id.supplier_taxes_id)
+        self._compute_tax_id()
 
         self._suggest_quantity()
         self._onchange_quantity()