diff --git a/packages/core-api/src/routing/RouteRef.ts b/packages/core-api/src/routing/RouteRef.ts
index d218d72fbb..eda16ccc91 100644
--- a/packages/core-api/src/routing/RouteRef.ts
+++ b/packages/core-api/src/routing/RouteRef.ts
@@ -31,13 +31,14 @@ export type RouteRefConfig<Params extends AnyParams> = {
   title: string;
 };
 
-class RouteRefBaseBase {
+class RouteRefBase {
   constructor(type: string, id: string) {
     this.toString = () => `routeRef{type=${type},id=${id}}`;
   }
 }
 
-export class RouteRefImpl<Params extends AnyParams> extends RouteRefBaseBase {
+export class RouteRefImpl<Params extends AnyParams> extends RouteRefBase
+  implements RouteRef<Params> {
   readonly [routeRefType] = 'absolute';
 
   constructor(private readonly config: RouteRefConfig<Params>) {
@@ -92,7 +93,7 @@ export function createRouteRef<
 export class ExternalRouteRefImpl<
   Params extends AnyParams,
   Optional extends boolean
-> extends RouteRefBaseBase {
+> extends RouteRefBase implements ExternalRouteRef<Params, Optional> {
   readonly [routeRefType] = 'external';
 
   constructor(
diff --git a/packages/core-api/src/routing/types.ts b/packages/core-api/src/routing/types.ts
index de6f991ec9..69de5345a5 100644
--- a/packages/core-api/src/routing/types.ts
+++ b/packages/core-api/src/routing/types.ts
@@ -28,7 +28,7 @@ export const routeRefType: unique symbol = getGlobalSingleton<any>(
 );
 
 export type RouteRef<Params extends AnyParams = any> = {
-  [routeRefType]: 'absolute';
+  readonly [routeRefType]: 'absolute';
 
   params: ParamKeys<Params>;
 
@@ -45,7 +45,7 @@ export type ExternalRouteRef<
   Params extends AnyParams = any,
   Optional extends boolean = any
 > = {
-  [routeRefType]: 'external';
+  readonly [routeRefType]: 'external';
 
   params: ParamKeys<Params>;