diff --git a/lib/node-http-proxy/routing-proxy.js b/lib/node-http-proxy/routing-proxy.js
index 3216c82..b9b8a17 100644
--- a/lib/node-http-proxy/routing-proxy.js
+++ b/lib/node-http-proxy/routing-proxy.js
@@ -195,8 +195,10 @@ RoutingProxy.prototype.proxyRequest = function (req, res, options) {
     //
     if (!location) {
       try {
-        res.writeHead(404);
-        res.end();
+        if (!this.emit('notFound', req, res)) {
+          res.writeHead(404);
+          res.end();
+        }
       }
       catch (er) {
         console.error("res.writeHead/res.end error: %s", er.message);