=== modified file 'account/account_invoice.py'
--- account/account_invoice.py	2014-02-05 10:03:24 +0000
+++ account/account_invoice.py	2014-03-01 07:42:03 +0000
@@ -1022,7 +1022,9 @@
             line = self.finalize_invoice_move_lines(cr, uid, inv, line)
 
             move = {
-                'ref': inv.reference and inv.reference or inv.name,
+                'ref': (inv.supplier_invoice_number and
+                        inv.supplier_invoice_number or
+                        (inv.reference and inv.reference or inv.name)),
                 'line_id': line,
                 'journal_id': journal_id,
                 'date': date,