diff --git a/docs/api.md b/docs/api.md
index a6ced9cf3e1..07120c4400a 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -48,7 +48,7 @@
     + [page.reload(options)](#pagereloadoptions)
     + [page.screenshot([options])](#pagescreenshotoptions)
     + [page.setContent(html)](#pagesetcontenthtml)
-    + [page.setHTTPHeaders(headers)](#pagesethttpheadersheaders)
+    + [page.setExtraHTTPHeaders(headers)](#pagesetextrahttpheadersheaders)
     + [page.setInPageCallback(name, callback)](#pagesetinpagecallbackname-callback)
     + [page.setRequestInterceptor(interceptor)](#pagesetrequestinterceptorinterceptor)
     + [page.setUserAgent(userAgent)](#pagesetuseragentuseragent)
@@ -544,10 +544,14 @@ Shortcut for [`keyboard.down`](#keyboarddownkey-options) and [`keyboard.up`](#ke
 - `html` <[string]> HTML markup to assign to the page.
 - returns: <[Promise]> Promise which resolves when the content is successfully assigned.
 
-#### page.setHTTPHeaders(headers)
-- `headers` <[Object]> Key-value set of additional http headers to be sent with every request.
+#### page.setExtraHTTPHeaders(headers)
+- `headers` <[Map]> A map of additional http headers to be sent with every request.
 - returns: <[Promise]> Promise which resolves when additional headers are installed
 
+The extra HTTP headers will be sent with every request the page initiates.
+
+> **NOTE** page.setExtraHTTPHeaders does not guarantee the order of headers in the outgoing requests.
+
 #### page.setInPageCallback(name, callback)
 - `name` <[string]> Name of the callback to be assigned on window object
 - `callback` <[function]> Callback function which will be called in puppeteer's context.
diff --git a/lib/NetworkManager.js b/lib/NetworkManager.js
index 91cc681339f..7e997abedc9 100644
--- a/lib/NetworkManager.js
+++ b/lib/NetworkManager.js
@@ -24,9 +24,10 @@ class NetworkManager extends EventEmitter {
     super();
     this._client = client;
     this._requestInterceptor = null;
-    /* @type {!Map<string, !Request>} */
+    /** @type {!Map<string, !Request>} */
     this._idToRequest = new Map();
-    this._httpHeaders = {};
+    /** @type {!Map<string, string>} */
+    this._extraHTTPHeaders = new Map();
 
     this._client.on('Network.requestWillBeSent', this._onRequestWillBeSent.bind(this));
     this._client.on('Network.requestIntercepted', this._onRequestIntercepted.bind(this));
@@ -36,22 +37,22 @@ class NetworkManager extends EventEmitter {
   }
 
   /**
-   * @param {!Object} headers
+   * @param {!Map<string, string>} extraHTTPHeaders
    * @return {!Promise}
    */
-  async setHTTPHeaders(headers) {
-    this._httpHeaders = {};
-    // Note: header names are case-insensitive.
-    for (let key of Object.keys(headers))
-      this._httpHeaders[key.toLowerCase()] = headers[key];
-    return this._client.send('Network.setExtraHTTPHeaders', { headers });
+  async setExtraHTTPHeaders(extraHTTPHeaders) {
+    this._extraHTTPHeaders = new Map(extraHTTPHeaders);
+    let headers = {};
+    for (let entry of extraHTTPHeaders.entries())
+      headers[entry[0]] = entry[1];
+    await this._client.send('Network.setExtraHTTPHeaders', { headers });
   }
 
   /**
-   * @return {!Object}
+   * @return {!Map<string, string>}
    */
-  httpHeaders() {
-    return Object.assign({}, this._httpHeaders);
+  extraHTTPHeaders() {
+    return new Map(this._extraHTTPHeaders);
   }
 
   /**
diff --git a/lib/Page.js b/lib/Page.js
index 8a172640618..d886b3ba814 100644
--- a/lib/Page.js
+++ b/lib/Page.js
@@ -161,11 +161,11 @@ class Page extends EventEmitter {
   }
 
   /**
-   * @param {!Object} headers
+   * @param {!Map<string, string>} headers
    * @return {!Promise}
    */
-  async setHTTPHeaders(headers) {
-    return this._networkManager.setHTTPHeaders(headers);
+  async setExtraHTTPHeaders(headers) {
+    return this._networkManager.setExtraHTTPHeaders(headers);
   }
 
   /**
@@ -250,7 +250,7 @@ class Page extends EventEmitter {
     const listener = helper.addEventListener(this._networkManager, NetworkManager.Events.Response, response => responses.set(response.url, response));
     const result = watcher.waitForNavigation();
 
-    const referrer = this._networkManager.httpHeaders()['referer'];
+    const referrer = this._networkManager.extraHTTPHeaders().get('referer');
     try {
       // Await for the command to throw exception in case of illegal arguments.
       await this._client.send('Page.navigate', {url, referrer});
diff --git a/phantom_shim/WebPage.js b/phantom_shim/WebPage.js
index 076611edca9..82f650ac2bf 100644
--- a/phantom_shim/WebPage.js
+++ b/phantom_shim/WebPage.js
@@ -284,7 +284,7 @@ class WebPage {
    */
   set customHeaders(value) {
     this._customHeaders = value;
-    await(this._page.setHTTPHeaders(value));
+    await(this._page.setExtraHTTPHeaders(new Map(Object.entries(value))));
   }
 
   /**
diff --git a/test/test.js b/test/test.js
index f8414c4f779..ca51a7a22da 100644
--- a/test/test.js
+++ b/test/test.js
@@ -611,9 +611,9 @@ describe('Puppeteer', function() {
       expect(response.ok).toBe(true);
     }));
     it('should show custom HTTP headers', SX(async function() {
-      await page.setHTTPHeaders({
+      await page.setExtraHTTPHeaders(new Map(Object.entries({
         foo: 'bar'
-      });
+      })));
       page.setRequestInterceptor(request => {
         expect(request.headers.get('foo')).toBe('bar');
         request.continue();
@@ -1046,9 +1046,11 @@ describe('Puppeteer', function() {
       expect(await page.evaluate(() => navigator.userAgent)).toContain('Safari');
     }));
   });
-  describe('Page.setHTTPHeaders', function() {
+  describe('Page.setExtraHTTPHeaders', function() {
     it('should work', SX(async function() {
-      page.setHTTPHeaders({'foo': 'bar'});
+      await page.setExtraHTTPHeaders(new Map(Object.entries({
+        foo: 'bar'
+      })));
       page.navigate(EMPTY_PAGE);
       let request = await server.waitForRequest('/empty.html');
       expect(request.headers['foo']).toBe('bar');