diff --git a/lib/types/thread-types.js b/lib/types/thread-types.js
--- a/lib/types/thread-types.js
+++ b/lib/types/thread-types.js
@@ -77,6 +77,7 @@
   +name: string,
   +permissions: ThreadRolePermissionsBlob,
   +isDefault: boolean,
+  +specialRole?: ?number,
 };
 export const legacyRoleInfoValidator: TInterface<LegacyRoleInfo> =
   tShape<LegacyRoleInfo>({
@@ -84,6 +85,7 @@
     name: t.String,
     permissions: threadRolePermissionsBlobValidator,
     isDefault: t.Boolean,
+    specialRole: t.maybe(t.Number),
   });
 
 export type RoleInfo = LegacyRoleInfo | MinimallyEncodedRoleInfo;