diff --git a/lib/middleware.js b/lib/middleware.js
index 4a2365a20..7d6a3abe6 100644
--- a/lib/middleware.js
+++ b/lib/middleware.js
@@ -79,7 +79,7 @@ module.exports = function wrapper(context) {
           contentType += '; charset=UTF-8';
         }
 
-        if (!res.getHeader('Content-Type')) {
+        if (!res.getHeader || (typeof res.getHeader === 'function' && !res.getHeader('Content-Type'))) {
           res.setHeader('Content-Type', contentType);
         }
         res.setHeader('Content-Length', content.length);
diff --git a/package-lock.json b/package-lock.json
index 381934a71..e8b4fb7db 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "webpack-dev-middleware",
-  "version": "3.6.1",
+  "version": "3.6.2",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index 586838168..ca372fbf2 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "webpack-dev-middleware",
-  "version": "3.6.1",
+  "version": "3.6.2",
   "description": "A development middleware for webpack",
   "main": "index.js",
   "files": [