diff --git a/addons/account/invoice.py b/addons/account/invoice.py
index 7307a2fbd3b..b995014bd23 100644
--- a/addons/account/invoice.py
+++ b/addons/account/invoice.py
@@ -836,7 +836,7 @@ class account_invoice(osv.osv):
         }
 
         lines = [(0, 0, l1), (0, 0, l2)]
-        move = {'ref': inv.number, 'line_id': lines, 'journal_id': pay_journal_id, 'period_id': period_id, 'date': date}
+        move = {'ref': invoice.number, 'line_id': lines, 'journal_id': pay_journal_id, 'period_id': period_id, 'date': date}
         move_id = self.pool.get('account.move').create(cr, uid, move)
 
         line_ids = []