diff --git a/application/WarehouseArticlePacket/WarehouseArticlePacketModel.php b/application/WarehouseArticlePacket/WarehouseArticlePacketModel.php
index 5c98ee963..bf30fe54f 100644
--- a/application/WarehouseArticlePacket/WarehouseArticlePacketModel.php
+++ b/application/WarehouseArticlePacket/WarehouseArticlePacketModel.php
@@ -3,7 +3,7 @@
 class WarehouseArticlePacketModel extends TTCrudBaseModel {
     public int $id;
     public string $title;
-    public string $externalArticleNumber;
+    public ?string $externalArticleNumber;
     public string $description;
     public string $category;
     public ?float $overrideSellPrice;