diff --git a/CHANGELOG b/CHANGELOG
index dba091d779..3cac8c054e 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Allow to change the carrier until the shipment is done
+
 Version 3.4.0 - 2014-10-20
 * Bug fixes (see mercurial logs for details)
 
diff --git a/stock.py b/stock.py
index d1f615a35b..e34772e9a4 100644
--- a/stock.py
+++ b/stock.py
@@ -12,7 +12,8 @@ __metaclass__ = PoolMeta
 class ShipmentOut:
     __name__ = 'stock.shipment.out'
     carrier = fields.Many2One('carrier', 'Carrier', states={
-            'readonly': Eval('state') != 'draft',
+            'readonly': ~Eval('state').in_(['draft', 'waiting', 'assigned',
+                    'packed']),
             },
         depends=['state'])
     cost_currency = fields.Many2One('currency.currency',