diff --git a/stock.py b/stock.py
index b0ba65da81..6cbf13e0dc 100644
--- a/stock.py
+++ b/stock.py
@@ -185,8 +185,6 @@ class ShippingMixin:
     @classmethod
     def __setup__(cls):
         super().__setup__()
-        # The shipment reference will be set by the shipping service
-        cls.reference.readonly = True
         cls._buttons.update({
                 'create_shipping': {
                     'invisible': (Eval('reference', False)