diff --git a/addons/account/invoice.py b/addons/account/invoice.py
index 0ddd831fa13..cd8ba660ba7 100644
--- a/addons/account/invoice.py
+++ b/addons/account/invoice.py
@@ -1064,7 +1064,7 @@ class account_invoice_line(osv.osv):
             taxes = res.supplier_taxes_id and res.supplier_taxes_id or (a and self.pool.get('account.account').browse(cr, uid,a).tax_ids or False)
             tax_id = self.pool.get('account.fiscal.position').map_tax(cr, uid, fpos, taxes)
         if type in ('in_invoice', 'in_refund'):
-            to_update = self.product_id_change_unit_price_inv(cr, uid, tax_id, price_unit, qty, address_invoice_id, product, partner_id, context=context)
+            to_update = self.product_id_change_unit_price_inv(cr, uid, tax_id, price_unit or res.standard_price, qty, address_invoice_id, product, partner_id, context=context)
             result.update(to_update)
         else:
             result.update({'price_unit': res.list_price, 'invoice_line_tax_id': tax_id})