diff --git a/hdr_schemata/models/GWDM/2.0/schema.json b/hdr_schemata/models/GWDM/2.0/schema.json
index f26fc09..1f276b6 100644
--- a/hdr_schemata/models/GWDM/2.0/schema.json
+++ b/hdr_schemata/models/GWDM/2.0/schema.json
@@ -622,7 +622,8 @@
                         }
                   },
                   "title": "DatasetLinkage",
-                  "type": "object"
+                  "type": "object",
+                  "default": null
             },
             "DeliveryLeadTimeV2": {
                   "enum": [