diff --git a/addons/stock/models/stock_picking.py b/addons/stock/models/stock_picking.py
index 1a91fd968d1..f2b05321384 100644
--- a/addons/stock/models/stock_picking.py
+++ b/addons/stock/models/stock_picking.py
@@ -911,6 +911,7 @@ class Picking(models.Model):
             moves.action_confirm()
         return moves
 
+    @api.model
     def _prepare_values_extra_move(self, op, product, remaining_qty):
         """
         Creates an extra move when there is no corresponding original move to be copied