diff --git a/browser-sync/browser-sync.d.ts b/browser-sync/browser-sync.d.ts
index 9f081f663..f189f4ac0 100644
--- a/browser-sync/browser-sync.d.ts
+++ b/browser-sync/browser-sync.d.ts
@@ -283,7 +283,7 @@ declare module "browser-sync" {
         target?: string;
         middleware?: MiddlewareHandler;
         ws: boolean;
-        reqHeaders: (config) => Hash<any>;
+        reqHeaders: (config: any) => Hash<any>;
         proxyRes: (res: http.ServerResponse, req: http.ServerRequest, next: Function) => any;
     }