diff --git a/addons/stock/stock.py b/addons/stock/stock.py
index bd15c45e4216355a64c63a4b3687404787390eaf..7dc39c150a2b65c62d6a3146523b91d09f3d4e38 100644
--- a/addons/stock/stock.py
+++ b/addons/stock/stock.py
@@ -1641,7 +1641,7 @@ class stock_move(osv.osv):
         'location_dest_id': fields.many2one('stock.location', 'Destination Location', required=True,states={'done': [('readonly', True)]}, select=True, help="Location where the system will stock the finished products."),
         'partner_id': fields.many2one('res.partner', 'Destination Address ', states={'done': [('readonly', True)]}, help="Optional address where goods are to be delivered, specifically used for allotment"),
 
-        'prodlot_id': fields.many2one('stock.production.lot', 'Serial Number', states={'done': [('readonly', True)]}, help="Serial number is used to put a serial number on the production", select=True),
+        'prodlot_id': fields.many2one('stock.production.lot', 'Serial Number', help="Serial number is used to put a serial number on the production", select=True, ondelete='restrict'),
         'tracking_id': fields.many2one('stock.tracking', 'Pack', select=True, states={'done': [('readonly', True)]}, help="Logistical shipping unit: pallet, box, pack ..."),
 
         'auto_validate': fields.boolean('Auto Validate'),