diff --git a/platform/chromium/polyfill.js b/platform/chromium/polyfill.js
deleted file mode 100644
index 9530968dc..000000000
--- a/platform/chromium/polyfill.js
+++ /dev/null
@@ -1,74 +0,0 @@
-/*******************************************************************************
-
-    uBlock Origin - a browser extension to block requests.
-    Copyright (C) 2014-2017 The uBlock Origin authors
-
-    This program is free software: you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see {http://www.gnu.org/licenses/}.
-
-    Home: https://github.com/gorhill/uBlock
-*/
-
-// For background page or non-background pages
-
-/* exported objectAssign */
-
-'use strict';
-
-/******************************************************************************/
-/******************************************************************************/
-
-// https://github.com/gorhill/uBlock/issues/1067
-// https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/String/startsWith
-// Firefox 17/Chromium 41 supports `startsWith`.
-
-if ( String.prototype.startsWith instanceof Function === false ) {
-    String.prototype.startsWith = function(needle, pos) {
-        if ( typeof pos !== 'number' ) {
-            pos = 0;
-        }
-        return this.lastIndexOf(needle, pos) === pos;
-    };
-}
-
-/******************************************************************************/
-
-// https://github.com/gorhill/uBlock/issues/1067
-// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/endsWith
-// Firefox 17/Chromium 41 supports `endsWith`.
-
-if ( String.prototype.endsWith instanceof Function === false ) {
-    String.prototype.endsWith = function(needle, pos) {
-        if ( typeof pos !== 'number' ) {
-            pos = this.length;
-        }
-        pos -= needle.length;
-        return this.indexOf(needle, pos) === pos;
-    };
-}
-
-/******************************************************************************/
-
-// As per MDN, Object.assign appeared first in Chromium 45.
-// https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#Browser_compatibility
-
-var objectAssign = Object.assign || function(target, source) {
-    var keys = Object.keys(source);
-    for ( var i = 0, n = keys.length, key; i < n; i++ ) {
-        key = keys[i];
-        target[key] = source[key];
-    }
-    return target;
-};
-
-/******************************************************************************/
diff --git a/platform/webext/polyfill.js b/platform/webext/polyfill.js
deleted file mode 100644
index 78e57a994..000000000
--- a/platform/webext/polyfill.js
+++ /dev/null
@@ -1,30 +0,0 @@
-/*******************************************************************************
-
-    uBlock Origin - a browser extension to block requests.
-    Copyright (C) 2016 The uBlock Origin authors
-
-    This program is free software: you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see {http://www.gnu.org/licenses/}.
-
-    Home: https://github.com/gorhill/uBlock
-*/
-
-// For background page or non-background pages
-
-'use strict';
-
-/******************************************************************************/
-
-var objectAssign = Object.assign;
-
-/******************************************************************************/
diff --git a/src/background.html b/src/background.html
index 603027fe1..cf7838bef 100644
--- a/src/background.html
+++ b/src/background.html
@@ -5,7 +5,6 @@
 <title>uBlock Origin</title>
 </head>
 <body>
-<script src="js/polyfill.js"></script>
 <script src="lib/punycode.js"></script>
 <script src="lib/publicsuffixlist.js"></script>
 <script src="js/vapi.js"></script>
diff --git a/src/js/background.js b/src/js/background.js
index eba4bbe7a..786be0d94 100644
--- a/src/js/background.js
+++ b/src/js/background.js
@@ -20,8 +20,6 @@
 */
 
 
-/* global objectAssign */
-
 'use strict';
 
 /******************************************************************************/
@@ -96,7 +94,7 @@ var µBlock = (function() { // jshint ignore:line
 
         hiddenSettingsDefault: hiddenSettingsDefault,
         hiddenSettings: (function() {
-            var out = objectAssign({}, hiddenSettingsDefault),
+            var out = Object.assign({}, hiddenSettingsDefault),
                 json = vAPI.localStorage.getItem('immediateHiddenSettings');
             if ( typeof json === 'string' ) {
                 try {
diff --git a/src/js/storage.js b/src/js/storage.js
index 098fced62..91cbf893d 100644
--- a/src/js/storage.js
+++ b/src/js/storage.js
@@ -19,7 +19,7 @@
     Home: https://github.com/gorhill/uBlock
 */
 
-/* global objectAssign, punycode, publicSuffixList */
+/* global punycode, publicSuffixList */
 
 'use strict';
 
@@ -146,7 +146,7 @@
 /******************************************************************************/
 
 µBlock.hiddenSettingsFromString = function(raw) {
-    var out = objectAssign({}, this.hiddenSettingsDefault),
+    var out = Object.assign({}, this.hiddenSettingsDefault),
         lineIter = new this.LineIterator(raw),
         line, matches, name, value;
     while ( lineIter.eot() === false ) {
@@ -575,7 +575,7 @@
             if ( entries.hasOwnProperty(assetKey) === false ) { continue; }
             entry = entries[assetKey];
             if ( entry.content !== 'filters' ) { continue; }
-            newAvailableLists[assetKey] = objectAssign({}, entry);
+            newAvailableLists[assetKey] = Object.assign({}, entry);
         }
 
         // Load set of currently selected filter lists.