diff --git a/src/middlewares/modded.express.mung.js b/src/middlewares/modded.express.mung.ts
similarity index 96%
rename from src/middlewares/modded.express.mung.js
rename to src/middlewares/modded.express.mung.ts
index e8459b38..8f65942c 100644
--- a/src/middlewares/modded.express.mung.js
+++ b/src/middlewares/modded.express.mung.ts
@@ -5,7 +5,7 @@
 
 'use strict';
 
-let mung = {};
+let mung: any = {};
 let faux_fin = { end: () => null };
 
 function isScalar(v) {
@@ -135,7 +135,7 @@ mung.headersAsync = function headersAsync(fn) {
       return mung.onError(e, req, res, next);
     };
     function headers_async_hook() {
-      if (res.headersSent) return original.apply(this, args);
+      if (res.headersSent) return original.apply(this, null); // (this, args)
       let args = arguments;
       res.end = () => null;
       try {
@@ -145,9 +145,9 @@ mung.headersAsync = function headersAsync(fn) {
             if (res.headersSent) return;
             original.apply(this, args);
           })
-          .catch(e => onError(e, req, res, next));
+          .catch(e => onError(e));
       } catch (e) {
-        onError(e, req, res, next);
+        onError(e);
       }
     }
     res.end = headers_async_hook;
@@ -205,4 +205,4 @@ mung.write = function write(fn, options = {}) {
   };
 };
 
-module.exports = mung;
+export default mung;
diff --git a/src/middlewares/openapi.response.validator.ts b/src/middlewares/openapi.response.validator.ts
index 4b2b1a3e..b8a1cc38 100644
--- a/src/middlewares/openapi.response.validator.ts
+++ b/src/middlewares/openapi.response.validator.ts
@@ -1,5 +1,6 @@
 import ono from 'ono';
 import * as Ajv from 'ajv';
+import mung from './modded.express.mung';
 import { createResponseAjv } from './ajv';
 import {
   extractContentType,
@@ -7,7 +8,6 @@ import {
   validationError,
 } from './util';
 
-const mung = require('./modded.express.mung');
 const TYPE_JSON = 'application/json';
 
 export class ResponseValidator {
@@ -25,6 +25,7 @@ export class ResponseValidator {
   }
 
   validate() {
+    console.log('=======', mung);
     return mung.json((body, req: any, res) => {
       if (req.openapi) {
         const responses = req.openapi.schema && req.openapi.schema.responses;
diff --git a/tsconfig.json b/tsconfig.json
index 17f75919..3a1c4894 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -10,5 +10,5 @@
   },
   
   "exclude": ["node_modules"],
-  "include": ["typings.d.ts", "src/**/*.ts", "src/middlewares/modded.express.mung.js"]
+  "include": ["typings.d.ts", "src/**/*.ts", "src/middlewares/modded.express.mung.ts"]
 }