diff --git a/.eslintignore b/.eslintignore
new file mode 100644
index 00000000..62562b74
--- /dev/null
+++ b/.eslintignore
@@ -0,0 +1,2 @@
+coverage
+node_modules
diff --git a/.eslintrc b/.eslintrc
new file mode 100644
index 00000000..e3578aad
--- /dev/null
+++ b/.eslintrc
@@ -0,0 +1,3 @@
+{
+  "extends": "standard"
+}
diff --git a/.travis.yml b/.travis.yml
index 0280df88..c5c1f197 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,15 +6,24 @@ node_js:
   - "1.8"
   - "2.5"
   - "3.3"
-  - "4.2"
-  - "5.4"
+  - "4.4"
+  - "5.11"
+  - "6.1"
 sudo: false
+cache:
+  directories:
+    - node_modules
 before_install:
   # Setup Node.js version-specific dependencies
-  - "test $TRAVIS_NODE_VERSION != '0.8' || npm rm --save-dev istanbul"
+  - "test $TRAVIS_NODE_VERSION != '0.8' || npm rm --save-dev eslint eslint-config-standard eslint-plugin-promise eslint-plugin-standard istanbul"
+
+  # Update Node.js modules
+  - "test ! -d node_modules || npm prune"
+  - "test ! -d node_modules || npm rebuild"
 script:
   # Run test script, depending on istanbul install
   - "test ! -z $(npm -ps ls istanbul) || npm test"
   - "test   -z $(npm -ps ls istanbul) || npm run-script test-travis"
+  - "test   -z $(npm -ps ls eslint  ) || npm run-script lint"
 after_script:
   - "test -e ./coverage/lcov.info && npm install coveralls@2 && cat ./coverage/lcov.info | coveralls"
diff --git a/HISTORY.md b/HISTORY.md
index 4f68cf9a..663f0de0 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -1,3 +1,16 @@
+1.6.2 / 2016-05-12
+==================
+
+  * deps: accepts@~1.3.3
+    - deps: mime-types@~2.1.11
+    - deps: negotiator@0.6.1
+  * deps: bytes@2.3.0
+    - Drop partial bytes on all parsed units
+    - Fix parsing byte string that looks like hex
+    - perf: hoist regular expressions
+  * deps: compressible@~2.0.8
+    - deps: mime-db@'>= 1.23.0 < 2'
+
 1.6.1 / 2016-01-19
 ==================
 
diff --git a/index.js b/index.js
index 05deb305..e6c494ce 100644
--- a/index.js
+++ b/index.js
@@ -21,6 +21,8 @@ var debug = require('debug')('compression')
 var onHeaders = require('on-headers')
 var vary = require('vary')
 var zlib = require('zlib')
+var OutgoingMessage = require('http').OutgoingMessage
+var hasCallback = (OutgoingMessage.prototype.write.length === 3)
 
 /**
  * Module exports.
@@ -39,12 +41,12 @@ var cacheControlNoTransformRegExp = /(?:^|,)\s*?no-transform\s*?(?:,|$)/
 /**
  * Compress response data with gzip / deflate.
  *
- * @param {Object} options
+ * @param {Object} [options]
  * @return {Function} middleware
  * @public
  */
 
-function compression(options) {
+function compression (options) {
   var opts = options || {}
 
   // options
@@ -55,17 +57,19 @@ function compression(options) {
     threshold = 1024
   }
 
-  return function compression(req, res, next){
+  return function compression (req, res, next) {
     var ended = false
     var length
     var listeners = []
-    var write = res.write
-    var on = res.on
-    var end = res.end
     var stream
+    var noop = function () {}
+
+    res._end = res.end
+    res._write = res.write
+    var _on = res.on
 
     // flush
-    res.flush = function flush() {
+    res.flush = function flush () {
       if (stream) {
         stream.flush()
       }
@@ -73,25 +77,29 @@ function compression(options) {
 
     // proxy
 
-    res.write = function(chunk, encoding){
+    res.write = function write (chunk, encoding, cb) {
       if (ended) {
         return false
       }
 
+      cb = hasCallback ? cb : null
+
       if (!this._header) {
         this._implicitHeader()
       }
 
       return stream
-        ? stream.write(new Buffer(chunk, encoding))
-        : write.call(this, chunk, encoding)
-    };
+        ? stream.write(new Buffer(chunk, encoding), cb)
+        : res._write.call(this, chunk, encoding, cb)
+    }
 
-    res.end = function(chunk, encoding){
+    res.end = function end (chunk, encoding, cb) {
       if (ended) {
         return false
       }
 
+      cb = hasCallback ? cb : null
+
       if (!this._header) {
         // estimate the length
         if (!this.getHeader('Content-Length')) {
@@ -102,7 +110,7 @@ function compression(options) {
       }
 
       if (!stream) {
-        return end.call(this, chunk, encoding)
+        return res._end.call(this, chunk, encoding, cb)
       }
 
       // mark ended
@@ -110,13 +118,13 @@ function compression(options) {
 
       // write Buffer for Node.js 0.8
       return chunk
-        ? stream.end(new Buffer(chunk, encoding))
-        : stream.end()
-    };
+        ? stream.end(new Buffer(chunk, encoding), null, cb)
+        : stream.end(null, null, cb)
+    }
 
-    res.on = function(type, listener){
+    res.on = function on (type, listener) {
       if (!listeners || type !== 'drain') {
-        return on.call(this, type, listener)
+        return _on.call(this, type, listener)
       }
 
       if (stream) {
@@ -129,13 +137,13 @@ function compression(options) {
       return this
     }
 
-    function nocompress(msg) {
+    function nocompress (msg) {
       debug('no compression: %s', msg)
-      addListeners(res, on, listeners)
+      addListeners(res, _on, listeners)
       listeners = null
     }
 
-    onHeaders(res, function(){
+    onHeaders(res, function onResponseHeaders () {
       // determine if request is filtered
       if (!filter(req, res)) {
         nocompress('filtered')
@@ -157,16 +165,16 @@ function compression(options) {
         return
       }
 
-      var encoding = res.getHeader('Content-Encoding') || 'identity';
+      var encoding = res.getHeader('Content-Encoding') || 'identity'
 
       // already encoded
-      if ('identity' !== encoding) {
+      if (encoding !== 'identity') {
         nocompress('already encoded')
         return
       }
 
       // head
-      if ('HEAD' === req.method) {
+      if (req.method === 'HEAD') {
         nocompress('HEAD request')
         return
       }
@@ -196,27 +204,27 @@ function compression(options) {
       addListeners(stream, stream.on, listeners)
 
       // header fields
-      res.setHeader('Content-Encoding', method);
-      res.removeHeader('Content-Length');
+      res.setHeader('Content-Encoding', method)
+      res.removeHeader('Content-Length')
 
       // compression
-      stream.on('data', function(chunk){
-        if (write.call(res, chunk) === false) {
+      stream.on('data', function onStreamData (chunk) {
+        if (res._write.call(res, chunk) === false) {
           stream.pause()
         }
-      });
+      })
 
-      stream.on('end', function(){
-        end.call(res);
-      });
+      stream.on('end', function onStreamEnd () {
+        res._end.call(res)
+      })
 
-      on.call(res, 'drain', function() {
+      _on.call(res, 'drain', function onResponseDrain () {
         stream.resume()
-      });
-    });
+      })
+    })
 
-    next();
-  };
+    next()
+  }
 }
 
 /**
@@ -224,7 +232,7 @@ function compression(options) {
  * @private
  */
 
-function addListeners(stream, on, listeners) {
+function addListeners (stream, on, listeners) {
   for (var i = 0; i < listeners.length; i++) {
     on.apply(stream, listeners[i])
   }
@@ -234,7 +242,7 @@ function addListeners(stream, on, listeners) {
  * Get the length of a given chunk
  */
 
-function chunkLength(chunk, encoding) {
+function chunkLength (chunk, encoding) {
   if (!chunk) {
     return 0
   }
@@ -249,7 +257,7 @@ function chunkLength(chunk, encoding) {
  * @private
  */
 
-function shouldCompress(req, res) {
+function shouldCompress (req, res) {
   var type = res.getHeader('Content-Type')
 
   if (type === undefined || !compressible(type)) {
@@ -265,11 +273,11 @@ function shouldCompress(req, res) {
  * @private
  */
 
-function shouldTransform(req, res) {
+function shouldTransform (req, res) {
   var cacheControl = res.getHeader('Cache-Control')
 
   // Don't compress for Cache-Control: no-transform
   // https://tools.ietf.org/html/rfc7234#section-5.2.2.4
-  return !cacheControl
-    || !cacheControlNoTransformRegExp.test(cacheControl)
+  return !cacheControl ||
+    !cacheControlNoTransformRegExp.test(cacheControl)
 }
diff --git a/package.json b/package.json
index 498061ba..1dfff077 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "compression",
   "description": "Node.js compression middleware",
-  "version": "1.6.1",
+  "version": "1.6.2",
   "contributors": [
     "Douglas Christopher Wilson <doug@somethingdoug.com>",
     "Jonathan Ong <me@jongleberry.com> (http://jongleberry.com)"
@@ -9,16 +9,20 @@
   "license": "MIT",
   "repository": "expressjs/compression",
   "dependencies": {
-    "accepts": "~1.3.1",
-    "bytes": "2.2.0",
-    "compressible": "~2.0.7",
+    "accepts": "~1.3.3",
+    "bytes": "2.3.0",
+    "compressible": "~2.0.8",
     "debug": "~2.2.0",
     "on-headers": "~1.0.1",
     "vary": "~1.1.0"
   },
   "devDependencies": {
-    "istanbul": "0.4.2",
-    "mocha": "2.3.4",
+    "eslint": "2.9.0",
+    "eslint-config-standard": "5.3.1",
+    "eslint-plugin-promise": "1.1.0",
+    "eslint-plugin-standard": "1.3.2",
+    "istanbul": "0.4.3",
+    "mocha": "2.4.5",
     "supertest": "1.1.0"
   },
   "files": [
@@ -30,6 +34,7 @@
     "node": ">= 0.8.0"
   },
   "scripts": {
+    "lint": "eslint **/*.js",
     "test": "mocha --check-leaks --reporter spec --bail",
     "test-cov": "istanbul cover node_modules/mocha/bin/_mocha -- --check-leaks --reporter dot",
     "test-travis": "istanbul cover node_modules/mocha/bin/_mocha --report lcovonly -- --check-leaks --reporter spec"
diff --git a/test/.eslintrc b/test/.eslintrc
new file mode 100644
index 00000000..29c15b08
--- /dev/null
+++ b/test/.eslintrc
@@ -0,0 +1,5 @@
+{
+  "env": {
+	  "mocha": true
+  }
+}
diff --git a/test/compression.js b/test/compression.js
index 26e0ca26..06e31c66 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -1,13 +1,15 @@
 var assert = require('assert')
-var bytes = require('bytes');
-var crypto = require('crypto');
-var http = require('http');
-var request = require('supertest');
+var bytes = require('bytes')
+var crypto = require('crypto')
+var http = require('http')
+var request = require('supertest')
+var OutgoingMessage = http.OutgoingMessage
+var hasCallbacks = (OutgoingMessage.prototype.write.length === 3)
 
-var compression = require('..');
+var compression = require('..')
 
-describe('compression()', function(){
-  it('should skip HEAD', function(done){
+describe('compression()', function () {
+  it('should skip HEAD', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
       res.end('hello, world')
@@ -20,7 +22,7 @@ describe('compression()', function(){
     .expect(200, done)
   })
 
-  it('should skip unknown accept-encoding', function(done){
+  it('should skip unknown accept-encoding', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
       res.end('hello, world')
@@ -33,7 +35,7 @@ describe('compression()', function(){
     .expect(200, done)
   })
 
-  it('should skip if content-encoding already set', function(done){
+  it('should skip if content-encoding already set', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
       res.setHeader('Content-Encoding', 'x-custom')
@@ -47,7 +49,7 @@ describe('compression()', function(){
     .expect(200, 'hello, world', done)
   })
 
-  it('should set Vary', function(done){
+  it('should set Vary', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
       res.end('hello, world')
@@ -60,7 +62,7 @@ describe('compression()', function(){
     .expect('Vary', 'Accept-Encoding', done)
   })
 
-  it('should set Vary even if Accept-Encoding is not set', function(done){
+  it('should set Vary even if Accept-Encoding is not set', function (done) {
     var server = createServer({ threshold: 1000 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
       res.end('hello, world')
@@ -73,7 +75,7 @@ describe('compression()', function(){
     .expect(200, done)
   })
 
-  it('should not set Vary if Content-Type does not pass filter', function(done){
+  it('should not set Vary if Content-Type does not pass filter', function (done) {
     var server = createServer(null, function (req, res) {
       res.setHeader('Content-Type', 'image/jpeg')
       res.end()
@@ -85,7 +87,7 @@ describe('compression()', function(){
     .expect(200, done)
   })
 
-  it('should set Vary for HEAD request', function(done){
+  it('should set Vary for HEAD request', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
       res.end('hello, world')
@@ -97,7 +99,7 @@ describe('compression()', function(){
     .expect('Vary', 'Accept-Encoding', done)
   })
 
-  it('should transfer chunked', function(done){
+  it('should transfer chunked', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
       res.end('hello, world')
@@ -109,7 +111,7 @@ describe('compression()', function(){
     .expect('Transfer-Encoding', 'chunked', done)
   })
 
-  it('should remove Content-Length for chunked', function(done){
+  it('should remove Content-Length for chunked', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
       res.end('hello, world')
@@ -136,7 +138,7 @@ describe('compression()', function(){
     .expect(200, 'hello, world', done)
   })
 
-  it('should allow writing after close', function(done){
+  it('should allow writing after close', function (done) {
     // UGH
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
@@ -150,17 +152,17 @@ describe('compression()', function(){
 
     request(server)
     .get('/')
-    .end(function(){})
+    .end(function () {})
   })
 
-  it('should back-pressure when compressed', function(done){
+  it('should back-pressure when compressed', function (done) {
     var buf
     var client
     var drained = false
     var resp
     var server = createServer({ threshold: 0 }, function (req, res) {
       resp = res
-      res.on('drain', function(){
+      res.on('drain', function () {
         drained = true
       })
       res.setHeader('Content-Type', 'text/plain')
@@ -169,25 +171,26 @@ describe('compression()', function(){
     })
     var wait = 2
 
-    crypto.pseudoRandomBytes(1024 * 128, function(err, chunk){
+    crypto.pseudoRandomBytes(1024 * 128, function (err, chunk) {
+      if (err) return done(err)
       buf = chunk
       pressure()
     })
 
-    function complete(){
+    function complete () {
       if (--wait !== 0) return
       assert.ok(drained)
       done()
     }
 
-    function pressure(){
+    function pressure () {
       if (!buf || !resp || !client) return
 
       while (resp.write(buf) !== false) {
         resp.flush()
       }
 
-      resp.on('drain', function(){
+      resp.on('drain', function () {
         resp.write('end')
         resp.end()
       })
@@ -208,14 +211,14 @@ describe('compression()', function(){
     .end()
   })
 
-  it('should back-pressure when uncompressed', function(done){
+  it('should back-pressure when uncompressed', function (done) {
     var buf
     var client
     var drained = false
     var resp
-    var server = createServer({ filter: function(){ return false } }, function (req, res) {
+    var server = createServer({ filter: function () { return false } }, function (req, res) {
       resp = res
-      res.on('drain', function(){
+      res.on('drain', function () {
         drained = true
       })
       res.setHeader('Content-Type', 'text/plain')
@@ -224,25 +227,26 @@ describe('compression()', function(){
     })
     var wait = 2
 
-    crypto.pseudoRandomBytes(1024 * 128, function(err, chunk){
+    crypto.pseudoRandomBytes(1024 * 128, function (err, chunk) {
+      if (err) return done(err)
       buf = chunk
       pressure()
     })
 
-    function complete(){
+    function complete () {
       if (--wait !== 0) return
       assert.ok(drained)
       done()
     }
 
-    function pressure(){
+    function pressure () {
       if (!buf || !resp || !client) return
 
       while (resp.write(buf) !== false) {
         resp.flush()
       }
 
-      resp.on('drain', function(){
+      resp.on('drain', function () {
         resp.write('end')
         resp.end()
       })
@@ -304,8 +308,8 @@ describe('compression()', function(){
     .expect(200, done)
   })
 
-  describe('threshold', function(){
-    it('should not compress responses below the threshold size', function(done){
+  describe('threshold', function () {
+    it('should not compress responses below the threshold size', function (done) {
       var server = createServer({ threshold: '1kb' }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.setHeader('Content-Length', '12')
@@ -319,7 +323,7 @@ describe('compression()', function(){
       .expect(200, done)
     })
 
-    it('should compress responses above the threshold size', function(done){
+    it('should compress responses above the threshold size', function (done) {
       var server = createServer({ threshold: '1kb' }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.setHeader('Content-Length', '2048')
@@ -332,11 +336,11 @@ describe('compression()', function(){
       .expect('Content-Encoding', 'gzip', done)
     })
 
-    it('should compress when streaming without a content-length', function(done){
+    it('should compress when streaming without a content-length', function (done) {
       var server = createServer({ threshold: '1kb' }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.write('hello, ')
-        setTimeout(function(){
+        setTimeout(function () {
           res.end('world')
         }, 10)
       })
@@ -347,12 +351,12 @@ describe('compression()', function(){
       .expect('Content-Encoding', 'gzip', done)
     })
 
-    it('should not compress when streaming and content-length is lower than threshold', function(done){
+    it('should not compress when streaming and content-length is lower than threshold', function (done) {
       var server = createServer({ threshold: '1kb' }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.setHeader('Content-Length', '12')
         res.write('hello, ')
-        setTimeout(function(){
+        setTimeout(function () {
           res.end('world')
         }, 10)
       })
@@ -364,12 +368,12 @@ describe('compression()', function(){
       .expect(200, done)
     })
 
-    it('should compress when streaming and content-length is larger than threshold', function(done){
+    it('should compress when streaming and content-length is larger than threshold', function (done) {
       var server = createServer({ threshold: '1kb' }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.setHeader('Content-Length', '2048')
         res.write(new Buffer(1024))
-        setTimeout(function(){
+        setTimeout(function () {
           res.end(new Buffer(1024))
         }, 10)
       })
@@ -382,7 +386,7 @@ describe('compression()', function(){
 
     // res.end(str, encoding) broken in node.js 0.8
     var run = /^v0\.8\./.test(process.version) ? it.skip : it
-    run('should handle writing hex data', function(done){
+    run('should handle writing hex data', function (done) {
       var server = createServer({ threshold: 6 }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.end('2e2e2e2e', 'hex')
@@ -395,7 +399,7 @@ describe('compression()', function(){
       .expect(200, '....', done)
     })
 
-    it('should consider res.end() as 0 length', function(done){
+    it('should consider res.end() as 0 length', function (done) {
       var server = createServer({ threshold: 1 }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.end()
@@ -587,7 +591,7 @@ describe('compression()', function(){
         write()
       })
 
-      function write() {
+      function write () {
         chunks++
         if (chunks === 2) return resp.end()
         if (chunks > 2) return chunks--
@@ -602,7 +606,7 @@ describe('compression()', function(){
       .on('response', function (res) {
         assert.equal(res.headers['content-encoding'], 'gzip')
         res.on('data', write)
-        res.on('end', function(){
+        res.on('end', function () {
           assert.equal(chunks, 2)
           done()
         })
@@ -619,7 +623,7 @@ describe('compression()', function(){
         write()
       })
 
-      function write() {
+      function write () {
         chunks++
         if (chunks === 20) return resp.end()
         if (chunks > 20) return chunks--
@@ -634,7 +638,7 @@ describe('compression()', function(){
       .on('response', function (res) {
         assert.equal(res.headers['content-encoding'], 'gzip')
         res.on('data', write)
-        res.on('end', function(){
+        res.on('end', function () {
           assert.equal(chunks, 20)
           done()
         })
@@ -651,7 +655,7 @@ describe('compression()', function(){
         write()
       })
 
-      function write() {
+      function write () {
         chunks++
         if (chunks === 20) return resp.end()
         if (chunks > 20) return chunks--
@@ -666,7 +670,7 @@ describe('compression()', function(){
       .on('response', function (res) {
         assert.equal(res.headers['content-encoding'], 'deflate')
         res.on('data', write)
-        res.on('end', function(){
+        res.on('end', function () {
           assert.equal(chunks, 20)
           done()
         })
@@ -674,16 +678,82 @@ describe('compression()', function(){
       .end()
     })
   })
+
+  describe('when callbacks are used', function () {
+    it('should call the passed callbacks in the order passed when compressing', function (done) {
+      var callbackOutput = []
+      var server = createServer(null, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.write('Hello', null, function () {
+          callbackOutput.push(0)
+        })
+        res.write(' World', null, function () {
+          callbackOutput.push(1)
+        })
+        res.end(null, null, function () {
+          callbackOutput.push(2)
+        })
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect('Content-Encoding', 'gzip')
+      .end(function (err) {
+        if (err) {
+          throw new Error(err)
+        }
+        if (hasCallbacks) {
+          assert.equal(callbackOutput.length, 3)
+          assert.deepEqual(callbackOutput, [0, 1, 2])
+        }
+        done()
+      })
+    })
+
+    it('should call the passed callbacks in the order passed when not compressing', function (done) {
+      var callbackOutput = []
+      var server = createServer(null, function (req, res) {
+        res.setHeader('Cache-Control', 'no-transform')
+        res.setHeader('Content-Type', 'text/plain')
+        res.write('hello,', null, function () {
+          callbackOutput.push(0)
+        })
+        res.write(' world', null, function () {
+          callbackOutput.push(1)
+        })
+        res.end(null, null, function () {
+          callbackOutput.push(2)
+        })
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect('Cache-Control', 'no-transform')
+      .expect(shouldNotHaveHeader('Content-Encoding'))
+      .end(function (err) {
+        if (err) {
+          throw new Error(err)
+        }
+        if (hasCallbacks) {
+          assert.equal(callbackOutput.length, 3)
+          assert.deepEqual(callbackOutput, [0, 1, 2])
+        }
+        done()
+      })
+    })
+  })
 })
 
-function createServer(opts, fn) {
+function createServer (opts, fn) {
   var _compression = compression(opts)
   return http.createServer(function (req, res) {
     _compression(req, res, function (err) {
       if (err) {
         res.statusCode = err.status || 500
         res.end(err.message)
-        return;
+        return
       }
 
       fn(req, res)
@@ -691,13 +761,13 @@ function createServer(opts, fn) {
   })
 }
 
-function shouldHaveBodyLength(length) {
+function shouldHaveBodyLength (length) {
   return function (res) {
     assert.equal(res.text.length, length, 'should have body length of ' + length)
   }
 }
 
-function shouldNotHaveHeader(header) {
+function shouldNotHaveHeader (header) {
   return function (res) {
     assert.ok(!(header.toLowerCase() in res.headers), 'should not have header ' + header)
   }