diff --git a/schema/contentobject.schema.json b/schema/contentobject.schema.json
index 429349b..1281564 100644
--- a/schema/contentobject.schema.json
+++ b/schema/contentobject.schema.json
@@ -67,7 +67,6 @@
                   },
                   "_link": {
                     "type": "string",
-                    "isObjectId": true,
                     "title": "Source",
                     "_backboneForms": "Asset"
                   }
diff --git a/schema/course.schema.json b/schema/course.schema.json
index fa8b6fe..4f6cd0f 100644
--- a/schema/course.schema.json
+++ b/schema/course.schema.json
@@ -410,7 +410,6 @@
                   },
                   "_link": {
                     "type": "string",
-                    "isObjectId": true,
                     "title": "Source",
                     "_backboneForms": "Asset"
                   },