diff --git a/plugins/auth-backend/config.d.ts b/plugins/auth-backend/config.d.ts
index 075c5e7942..4c8430b33f 100644
--- a/plugins/auth-backend/config.d.ts
+++ b/plugins/auth-backend/config.d.ts
@@ -194,6 +194,6 @@ export interface Config {
     /**
      * Additional app origins to allow for authenticating
      */
-    experimentalExtraAllowedOrigins?: string;
+    experimentalExtraAllowedOrigins?: string[];
   };
 }