diff --git a/api/v1/swagger/definitions/order.json b/api/v1/swagger/definitions/order.json
index f3d07d3735..bbc1b24e33 100644
--- a/api/v1/swagger/definitions/order.json
+++ b/api/v1/swagger/definitions/order.json
@@ -13,7 +13,10 @@
             "description": "Identifier for the linked bibliographic record"
         },
         "created_by": {
-            "type": "integer",
+            "type": [
+                "integer",
+                "null"
+            ],
             "description": "Interal patron identifier of the order line creator"
         },
         "entry_date": {