diff --git a/application/WarehouseOrder/WarehouseOrderModel.php b/application/WarehouseOrder/WarehouseOrderModel.php
index ac4677800..3d7cbf339 100644
--- a/application/WarehouseOrder/WarehouseOrderModel.php
+++ b/application/WarehouseOrder/WarehouseOrderModel.php
@@ -23,7 +23,7 @@
 class WarehouseOrderModel extends TTCrudBaseModel {
     public int $id;
     public string $orderNumber;
-    public string $extReference;
+    public ?string $extReference;
     public int $distributorId;
     public string $delAddrCity;
     public string $delAddrEMail;
@@ -31,7 +31,7 @@ class WarehouseOrderModel extends TTCrudBaseModel {
     public string $delAddrName;
     public string $delAddrPLZ;
     public int $editor;
-    public string $note;
+    public ?string $note;
     public string $positions;
     public int $create;
     public int $createBy;