diff --git a/addons/stock/stock.py b/addons/stock/stock.py
index f25665852e5..819521ea3fd 100644
--- a/addons/stock/stock.py
+++ b/addons/stock/stock.py
@@ -1518,7 +1518,7 @@ class stock_picking(osv.osv):
                     op = operation
                     if (operation.qty_done < operation.product_qty):
                         new_operation = stock_operation_obj.copy(cr, uid, operation.id, {'product_qty': operation.qty_done,'qty_done': operation.qty_done}, context=context)
-                        stock_operation_obj.write(cr, uid, operation.id, {'product_qty': operation.product_qty - operation.qty_done,'qty_done': 0, 'lot_id': False}, context=context)
+                        stock_operation_obj.write(cr, uid, operation.id, {'product_qty': operation.product_qty - operation.qty_done,'qty_done': 0}, context=context)
                         op = stock_operation_obj.browse(cr, uid, new_operation, context=context)
                     pack_operation_ids.append(op.id)
                     if op.product_id and op.location_id and op.location_dest_id:
@@ -4097,7 +4097,7 @@ class stock_pack_operation(osv.osv):
             if pack_op.qty_done < pack_op.product_qty:
                 # we split the operation in two
                 op = self.copy(cr, uid, pack_op.id, {'product_qty': pack_op.qty_done, 'qty_done': pack_op.qty_done}, context=context)
-                self.write(cr, uid, [pack_op.id], {'product_qty': pack_op.product_qty - pack_op.qty_done, 'qty_done': 0, 'lot_id': False}, context=context)
+                self.write(cr, uid, [pack_op.id], {'product_qty': pack_op.product_qty - pack_op.qty_done, 'qty_done': 0}, context=context)
             processed_ids.append(op)
         self.write(cr, uid, processed_ids, {'processed': 'true'}, context=context)