diff --git a/addons/hr_expense/hr_expense.py b/addons/hr_expense/hr_expense.py
index edd7076dbb7..ebe1bc0f109 100644
--- a/addons/hr_expense/hr_expense.py
+++ b/addons/hr_expense/hr_expense.py
@@ -131,12 +131,10 @@ class hr_expense_expense(osv.osv):
         return True
 
     def invoice(self, cr, uid, ids, context=None):
+        if not ids: return []
         mod_obj = self.pool.get('ir.model.data')
         wkf_service = netsvc.LocalService("workflow")
         
-        if not ids: return []
-        exp = self.browse(cr, uid, ids[0], context=context)
-        
         voucher_ids = []
         for id in ids:
             wkf_service.trg_validate(uid, 'hr.expense.expense', id, 'invoice', cr)