diff --git a/routes/xref/lib/constants.ts b/routes/xref/lib/constants.ts
index 27046cf..18c4932 100644
--- a/routes/xref/lib/constants.ts
+++ b/routes/xref/lib/constants.ts
@@ -16,7 +16,7 @@ export const IDL_TYPES = new Set([
 
 // XXX: `CONCEPT_TYPES` includes `element`: otherwise it'll break many specs.
 // https://github.com/sidvishnoi/respec-xref-route/issues/57
-export const CONCEPT_TYPES = new Set(["_CONCEPT_", "dfn", "event", "element"]);
+export const CONCEPT_TYPES = new Set(["_CONCEPT_", "dfn", "event", "element", "permission"]);
 export const MARKUP_TYPES = new Set(["element", "element-attr", "attr-value"]);
 export const CSS_TYPES_INPUT = new Set([
   "property",