diff --git a/module.d.ts b/module.d.ts
index 0ec8158..e0aaa2b 100644
--- a/module.d.ts
+++ b/module.d.ts
@@ -1,4 +1,9 @@
 declare module 'fastify-better-flash' {
+  import { FastifyPluginCallback } from 'fastify'
+
   // eslint-disable-next-line @typescript-eslint/no-empty-interface
   export interface FlashSessionType {}
+
+  const betterflash: FastifyPluginCallback<() => string>
+  export default betterflash
 }