From 8abe45a003c30ea41a20ca1a6826641c6cf67f65 Mon Sep 17 00:00:00 2001
From: Matteo Collina <hello@matteocollina.com>
Date: Wed, 17 May 2017 12:44:27 +0200
Subject: [PATCH] Use res.headersSent to detect if the headers have been sent

---
 index.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index 87974ca..c1cc7dd 100644
--- a/index.js
+++ b/index.js
@@ -87,9 +87,10 @@ function finalhandler (req, res, options) {
     var headers
     var msg
     var status
+    var headersSent = res.headersSent || res._header
 
     // ignore 404 on in-flight response
-    if (!err && res._header) {
+    if (!err && headersSent) {
       debug('cannot 404 after headers sent')
       return
     }
@@ -125,7 +126,7 @@ function finalhandler (req, res, options) {
     }
 
     // cannot actually respond
-    if (res._header) {
+    if (headersSent) {
       debug('cannot %d after headers sent', status)
       req.socket.destroy()
       return