diff --git a/registered-json-schemas/PortalDataset.json b/registered-json-schemas/PortalDataset.json
index d60e8b54..52e682c6 100644
--- a/registered-json-schemas/PortalDataset.json
+++ b/registered-json-schemas/PortalDataset.json
@@ -266,6 +266,12 @@
         },
         "type": "array"
       },
+      "externalViewer": {
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
       "fundingAgency": {
         "items": {
           "description": "",