diff --git a/types/express-serve-static-core/index.d.ts b/types/express-serve-static-core/index.d.ts
index 334d09eac0..2e431d8ad3 100644
--- a/types/express-serve-static-core/index.d.ts
+++ b/types/express-serve-static-core/index.d.ts
@@ -575,10 +575,8 @@ export interface Response extends http.ServerResponse, Express.Response {
      *
      * @api public
      */
-    sendFile(path: string): void;
-    sendFile(path: string, options: any): void;
-    sendFile(path: string, fn: Errback): void;
-    sendFile(path: string, options: any, fn: Errback): void;
+    sendFile(path: string, fn?: Errback): void;
+    sendFile(path: string, options: any, fn?: Errback): void;
 
     /**
      * @deprecated Use sendFile instead.
@@ -610,11 +608,9 @@ export interface Response extends http.ServerResponse, Express.Response {
      *
      * This method uses `res.sendfile()`.
      */
-    download(path: string): void;
-    download(path: string, filename: string): void;
-    download(path: string, fn: Errback): void;
-    download(path: string, filename: string, fn: Errback): void;
-    download(path: string, filename: string, options: any, fn: Errback): void;
+    download(path: string, fn?: Errback): void;
+    download(path: string, filename: string, fn?: Errback): void;
+    download(path: string, filename: string, options: any, fn?: Errback): void;
 
     /**
      * Set _Content-Type_ response header with `type` through `mime.lookup()`