diff --git a/types/koa-static/index.d.ts b/types/koa-static/index.d.ts
index eaba7866c4..34ebc39d53 100644
--- a/types/koa-static/index.d.ts
+++ b/types/koa-static/index.d.ts
@@ -19,7 +19,7 @@ import { Middleware } from "koa";
 
 import { SendOptions } from "koa-send";
 
-declare function serve(root: string, opts?: serve.Options): Middleware;
+declare function serve(root: string, opts?: serve.Options): Middleware<{}>;
 
 declare namespace serve {
     interface Options extends SendOptions {