diff --git a/addons/stock/stock.py b/addons/stock/stock.py
index 5b89bfd78c5..8bcd0e886a9 100644
--- a/addons/stock/stock.py
+++ b/addons/stock/stock.py
@@ -632,7 +632,7 @@ class stock_picking(osv.osv):
         'move_lines': fields.one2many('stock.move', 'picking_id', 'Internal Moves', states={'done': [('readonly', True)], 'cancel': [('readonly', True)]}),
         'auto_picking': fields.boolean('Auto-Picking'),
         'address_id': fields.many2one('res.partner.address', 'Address', help="Address of partner"),
-        'partner_id': fields.related('address_id','partner_id',type='many2one',relation='res.partner',string='Partner'),
+        'partner_id': fields.related('address_id','partner_id',type='many2one',relation='res.partner',string='Partner',store=True),
         'invoice_state': fields.selection([
             ("invoiced", "Invoiced"),
             ("2binvoiced", "To Be Invoiced"),
@@ -973,7 +973,7 @@ class stock_picking(osv.osv):
             if not partner:
                 raise osv.except_osv(_('Error, no partner !'),
                     _('Please put a partner on the picking list if you want to generate invoice.'))
-            
+
             if not inv_type:
                 inv_type = self._get_invoice_type(picking)