diff --git a/InvenTree/order/serializers.py b/InvenTree/order/serializers.py
index cde3a80683..0b5ae3fcc1 100644
--- a/InvenTree/order/serializers.py
+++ b/InvenTree/order/serializers.py
@@ -235,6 +235,7 @@ class POLineItemReceiveSerializer(serializers.Serializer):
         help_text=_('Unique identifier field'),
         default='',
         required=False,
+        allow_null=True,
         allow_blank=True,
     )