diff --git a/addons/sale/sale.py b/addons/sale/sale.py
index 65991b798d8..3ed49f44b74 100644
--- a/addons/sale/sale.py
+++ b/addons/sale/sale.py
@@ -260,7 +260,7 @@ class sale_order(osv.osv):
         'invoice_quantity': fields.selection([('order', 'Ordered Quantities'), ('procurement', 'Shipped Quantities')], 'Invoice on', help="The sale order will automatically create the invoice proposition (draft invoice). Ordered and delivered quantities may not be the same. You have to choose if you want your invoice based on ordered or shipped quantities. If the product is a service, shipped quantities means hours spent on the associated tasks.", required=True, readonly=True, states={'draft': [('readonly', False)]}),
         'payment_term': fields.many2one('account.payment.term', 'Payment Term'),
         'fiscal_position': fields.many2one('account.fiscal.position', 'Fiscal Position'),
-        'company_id': fields.related('shop_id','company_id',type='many2one',relation='res.company',string='Company',store=True)
+        'company_id': fields.related('shop_id','company_id',type='many2one',relation='res.company',string='Company',store=True,readonly=True)
     }
     _defaults = {
         'picking_policy': 'direct',