diff --git a/addons/account/account_invoice.py b/addons/account/account_invoice.py
index eb362455cd9..4611e0ab240 100644
--- a/addons/account/account_invoice.py
+++ b/addons/account/account_invoice.py
@@ -1260,9 +1260,7 @@ class account_invoice(osv.osv):
             ref = invoice.reference
         else:
             ref = self._convert_ref(cr, uid, invoice.number)
-        partner = invoice.partner_id
-        if partner.parent_id and not partner.is_company:
-            partner = partner.parent_id
+        partner = self.pool['res.partner']._find_accounting_partner(invoice.partner_id)
         # Pay attention to the sign for both debit/credit AND amount_currency
         l1 = {
             'debit': direction * pay_amount>0 and direction * pay_amount,
@@ -1733,15 +1731,17 @@ class res_partner(osv.osv):
         'invoice_ids': fields.one2many('account.invoice.line', 'partner_id', 'Invoices', readonly=True),
     }
 
-    def _find_accounting_partner(self, part):
+    def _find_accounting_partner(self, partner):
         '''
         Find the partner for which the accounting entries will be created
         '''
+        # FIXME: after 7.0, to replace by function field partner.commercial_id
+
         #if the chosen partner is not a company and has a parent company, use the parent for the journal entries
         #because you want to invoice 'Agrolait, accounting department' but the journal items are for 'Agrolait'
-        if part.parent_id and not part.is_company:
-            part = part.parent_id
-        return part
+        while not partner.is_company and partner.parent_id:
+            partner = partner.parent_id
+        return partner
 
     def copy(self, cr, uid, id, default=None, context=None):
         default = default or {}