diff --git a/addons/purchase/purchase.py b/addons/purchase/purchase.py
index 200be4a593a..0227e74905f 100644
--- a/addons/purchase/purchase.py
+++ b/addons/purchase/purchase.py
@@ -46,7 +46,7 @@ class purchase_order(osv.osv):
             cur = order.pricelist_id.currency_id
             for line in order.order_line:
                val1 += line.price_subtotal
-               for c in self.pool.get('account.tax').compute_all(cr, uid, line.taxes_id, line.price_unit, line.product_qty, line.product_id.id, order.partner_id)['taxes']:
+               for c in self.pool.get('account.tax').compute_all(cr, uid, line.taxes_id, line.price_unit, line.product_qty, line.product_id, order.partner_id)['taxes']:
                     val += c.get('amount', 0.0)
             res[order.id]['amount_tax']=cur_obj.round(cr, uid, cur, val)
             res[order.id]['amount_untaxed']=cur_obj.round(cr, uid, cur, val1)
@@ -823,7 +823,7 @@ class purchase_order_line(osv.osv):
         cur_obj=self.pool.get('res.currency')
         tax_obj = self.pool.get('account.tax')
         for line in self.browse(cr, uid, ids, context=context):
-            taxes = tax_obj.compute_all(cr, uid, line.taxes_id, line.price_unit, line.product_qty)
+            taxes = tax_obj.compute_all(cr, uid, line.taxes_id, line.price_unit, line.product_qty, line.product_id, line.order_id.partner_id)
             cur = line.order_id.pricelist_id.currency_id
             res[line.id] = cur_obj.round(cr, uid, cur, taxes['total'])
         return res