diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ace0b35..8f59862 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -96,7 +96,7 @@ jobs:
         - name: Node.js 13.x
           node-version: "13.14"
 
-        - name: Node.js 13.x
+        - name: Node.js 14.x
           node-version: "14.21"
 
         - name: Node.js 15.x
diff --git a/README.md b/README.md
index 422e67f..102ae16 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,11 @@ property will be populated with an object. This object will have numeric propert
 corresponding to each wildcard (or capture group if RegExp object provided) and the
 `hostname` that was matched.
 
+Where the `hostname` of the request comes from depends on the type of server you're running.
+If you're running a raw Node.js/connect server, this comes from [`req.headers.host`](https://nodejs.org/dist/latest/docs/api/http.html#http_message_headers).
+If you're running an express v3 server, this comes from [`req.host`](http://expressjs.com/en/3x/api.html#req.host).
+If you're running an express v4 server, this comes from [`req.hostname`](http://expressjs.com/en/4x/api.html#req.hostname).
+
 ```js
 var connect = require('connect')
 var vhost = require('vhost')
diff --git a/index.js b/index.js
index 480fd19..82c39d2 100644
--- a/index.js
+++ b/index.js
@@ -74,7 +74,9 @@ function vhost (hostname, handle) {
  */
 
 function hostnameof (req) {
-  var host = req.headers.host
+  var host = req.hostname || // express v4
+    req.host || // express v3
+    req.headers.host // http
 
   if (!host) {
     return
diff --git a/test/test.js b/test/test.js
index 1e41c8d..68d5b98 100644
--- a/test/test.js
+++ b/test/test.js
@@ -1,4 +1,3 @@
-
 var assert = require('assert')
 var http = require('http')
 var request = require('supertest')
@@ -22,6 +21,44 @@ describe('vhost(hostname, server)', function () {
       .expect(200, 'tobi', done)
   })
 
+  it('should route by `req.hostname` (express v4)', function (done) {
+    var vhosts = []
+
+    vhosts.push(vhost('anotherhost.com', anotherhost))
+    vhosts.push(vhost('loki.com', loki))
+
+    var app = createServer(vhosts, null, function (req) {
+      req.hostname = 'anotherhost.com'
+    })
+
+    function anotherhost (req, res) { res.end('anotherhost') }
+    function loki (req, res) { res.end('loki') }
+
+    request(app)
+    .get('/')
+    .set('Host', 'tobi.com')
+    .expect(200, 'anotherhost', done)
+  })
+
+  it('should route by `req.host` (express v3)', function (done) {
+    var vhosts = []
+
+    vhosts.push(vhost('anotherhost.com', anotherhost))
+    vhosts.push(vhost('loki.com', loki))
+
+    var app = createServer(vhosts, null, function (req) {
+      req.host = 'anotherhost.com'
+    })
+
+    function anotherhost (req, res) { res.end('anotherhost') }
+    function loki (req, res) { res.end('loki') }
+
+    request(app)
+    .get('/')
+    .set('Host', 'tobi.com')
+    .expect(200, 'anotherhost', done)
+  })
+
   it('should ignore port in Host', function (done) {
     var app = createServer('tobi.com', function (req, res) {
       res.end('tobi')
@@ -44,6 +81,42 @@ describe('vhost(hostname, server)', function () {
       .expect(200, 'loopback', done)
   })
 
+  it('should support IPv6 literal in `req.host` with port (express v5)', function (done) {
+    var app = createServer('[::1]', function (req, res) {
+      res.end('loopback')
+    }, function (req) {
+      req.host = '[::1]:8080'
+    })
+
+    request(app)
+    .get('/')
+    .expect(200, 'loopback', done)
+  })
+
+  it('should support IPv6 literal in `req.hostname` (express v4)', function (done) {
+    var app = createServer('[::1]', function (req, res) {
+      res.end('loopback')
+    }, function (req) {
+      req.hostname = '[::1]'
+    })
+
+    request(app)
+    .get('/')
+    .expect(200, 'loopback', done)
+  })
+
+  it('should support IPv6 literal in `req.host` without port (express v3)', function (done) {
+    var app = createServer('[::1]', function (req, res) {
+      res.end('loopback')
+    }, function (req) {
+      req.host = '[::1]'
+    })
+
+    request(app)
+    .get('/')
+    .expect(200, 'loopback', done)
+  })
+
   it('should 404 unless matched', function (done) {
     var vhosts = []
 
@@ -215,12 +288,15 @@ describe('vhost(hostname, server)', function () {
   })
 })
 
-function createServer (hostname, server) {
+function createServer (hostname, server, pretest) {
   var vhosts = !Array.isArray(hostname)
     ? [vhost(hostname, server)]
     : hostname
 
   return http.createServer(function onRequest (req, res) {
+    // This allows you to perform changes to the request/response
+    // objects before our assertions
+    if (pretest) pretest(req, res)
     var index = 0
 
     function next (err) {