diff --git a/lib/jsdom.js b/lib/jsdom.js
index 0751f7d512..2d6b7a5b13 100644
--- a/lib/jsdom.js
+++ b/lib/jsdom.js
@@ -5,6 +5,8 @@ var request = require('request');
 var pkg = require('../package.json');
 
 var toFileUrl = require('./jsdom/utils').toFileUrl;
+var defineGetter = require('./jsdom/utils').defineGetter;
+var defineSetter = require('./jsdom/utils').defineSetter;
 var style = require('./jsdom/level2/style');
 var features = require('./jsdom/browser/documentfeatures');
 var dom = exports.dom = require('./jsdom/level3/index').dom;
@@ -18,17 +20,17 @@ exports.windowAugmentation = require('./jsdom/browser/index').windowAugmentation
 ['availableDocumentFeatures',
  'defaultDocumentFeatures',
  'applyDocumentFeatures'].forEach(function (propName) {
-  exports.__defineGetter__(propName, function () {
+  defineGetter(exports, propName, function () {
     return features[propName];
   });
-  exports.__defineSetter__(propName, function (val) {
+  defineSetter(exports, propName, function (val) {
     return features[propName] = val;
   });
 });
 
 exports.debugMode = false;
 
-exports.__defineGetter__('version', function() {
+defineGetter(exports, 'version', function() {
   return pkg.version;
 });
 
diff --git a/lib/jsdom/browser/index.js b/lib/jsdom/browser/index.js
index 31701a2ffd..cdf41ee692 100644
--- a/lib/jsdom/browser/index.js
+++ b/lib/jsdom/browser/index.js
@@ -11,6 +11,8 @@ var http          = require('http'),
     NOT_IMPLEMENTED = require('./utils').NOT_IMPLEMENTED,
     CSSStyleDeclaration = require('cssstyle').CSSStyleDeclaration,
     toFileUrl = require('../utils').toFileUrl,
+    defineGetter  = require('../utils').defineGetter,
+    defineSetter  = require('../utils').defineSetter,
     Contextify    = require('contextify');
 
 function matchesDontThrow(el, selector) {
@@ -406,7 +408,7 @@ var browserAugmentation = exports.browserAugmentation = function(dom, options) {
     return new dom.NodeList(this.ownerDocument || this, dom.mapper(this, filterByClassName));
   };
 
-  dom.Element.prototype.__defineGetter__('sourceIndex', function() {
+  defineGetter(dom.Element.prototype, 'sourceIndex', function() {
     /*
     * According to QuirksMode:
     * Get the sourceIndex of element x. This is also the index number for
@@ -423,15 +425,15 @@ var browserAugmentation = exports.browserAugmentation = function(dom, options) {
     }
   });
 
-  dom.Document.prototype.__defineGetter__('outerHTML', function() {
+  defineGetter(dom.Document.prototype, 'outerHTML', function() {
     return domToHtml(this, true);
   });
 
-  dom.Element.prototype.__defineGetter__('outerHTML', function() {
+  defineGetter(dom.Element.prototype, 'outerHTML', function() {
     return domToHtml(this, true);
   });
 
-  dom.Element.prototype.__defineGetter__('innerHTML', function() {
+  defineGetter(dom.Element.prototype, 'innerHTML', function() {
     if (/^(?:script|style)$/.test(this._tagName)) {
       var type = this.getAttribute('type');
       if (!type || /^text\//i.test(type) || /\/javascript$/i.test(type)) {
@@ -442,10 +444,10 @@ var browserAugmentation = exports.browserAugmentation = function(dom, options) {
     return domToHtml(this._childNodes, true);
   });
 
-  dom.Element.prototype.__defineSetter__('doctype', function() {
+  defineSetter(dom.Element.prototype, 'doctype', function() {
     throw new dom.DOMException(dom.NO_MODIFICATION_ALLOWED_ERR);
   });
-  dom.Element.prototype.__defineGetter__('doctype', function() {
+  defineGetter(dom.Element.prototype, 'doctype', function() {
     var r = null;
     if (this.nodeName == '#document') {
         if (this._doctype) {
@@ -455,7 +457,7 @@ var browserAugmentation = exports.browserAugmentation = function(dom, options) {
     return r;
   });
 
-  dom.Element.prototype.__defineSetter__('innerHTML', function(html) {
+  defineSetter(dom.Element.prototype, 'innerHTML', function(html) {
     //Clear the children first:
     var child;
     while ((child = this._childNodes[0])) {
@@ -472,11 +474,11 @@ var browserAugmentation = exports.browserAugmentation = function(dom, options) {
   });
 
 
-  dom.Document.prototype.__defineGetter__('innerHTML', function() {
+  defineGetter(dom.Document.prototype, 'innerHTML', function() {
     return domToHtml(this._childNodes, true);
   });
 
-  dom.Document.prototype.__defineSetter__('innerHTML', function(html) {
+  defineSetter(dom.Document.prototype, 'innerHTML', function(html) {
     //Clear the children first:
     var child;
     while ((child = this._childNodes[0])) {
@@ -585,11 +587,11 @@ var browserAugmentation = exports.browserAugmentation = function(dom, options) {
     return new dom.NodeList(this.ownerDocument || this, dom.mapper(this, filterByClassName));
   };
 
-  dom.Element.prototype.__defineGetter__('nodeName', function(val) {
+  defineGetter(dom.Element.prototype, 'nodeName', function(val) {
     return this._nodeName.toUpperCase();
   });
 
-  dom.Element.prototype.__defineGetter__('tagName', function(val) {
+  defineGetter(dom.Element.prototype, 'tagName', function(val) {
     var t = this._tagName.toUpperCase();
     //Document should not return a tagName
     if (this.nodeName === '#document') {
@@ -601,27 +603,27 @@ var browserAugmentation = exports.browserAugmentation = function(dom, options) {
   dom.Element.prototype.scrollTop = 0;
   dom.Element.prototype.scrollLeft = 0;
 
-  dom.Document.prototype.__defineGetter__('parentWindow', function() {
+  defineGetter(dom.Document.prototype, 'parentWindow', function() {
     if (!this._parentWindow) {
       this.parentWindow = exports.windowAugmentation(dom, {document: this, url: this.URL});
     }
     return this._parentWindow;
   });
 
-  dom.Document.prototype.__defineSetter__('parentWindow', function(window) {
+  defineSetter(dom.Document.prototype, 'parentWindow', function(window) {
     // Contextify does not support getters and setters, so we have to set them
     // on the original object instead.
     window._frame = function (name, frame) {
       if (typeof frame === 'undefined') {
         delete window[name];
       } else {
-        window.__defineGetter__(name, function () { return frame.contentWindow; });
+        defineGetter(window, name, function () { return frame.contentWindow; });
       }
     };
     this._parentWindow = window.getGlobal();
   });
 
-  dom.Document.prototype.__defineGetter__('defaultView', function() {
+  defineGetter(dom.Document.prototype, 'defaultView', function() {
     return this.parentWindow;
   });
 
diff --git a/lib/jsdom/level2/core.js b/lib/jsdom/level2/core.js
index 4fb5d1f480..63ce394378 100644
--- a/lib/jsdom/level2/core.js
+++ b/lib/jsdom/level2/core.js
@@ -1,4 +1,6 @@
 var core                     = require("../level1/core").dom.level1.core;
+var defineGetter = require('../utils').defineGetter;
+var defineSetter = require('../utils').defineSetter;
 
 // modify cloned instance for more info check: https://github.com/tmpvar/jsdom/issues/325
 core = Object.create(core);
@@ -103,7 +105,7 @@ core.DOMImplementation.prototype.createDocument = function(/* String */       na
   return document;
 };
 
-core.Node.prototype.__defineGetter__("ownerDocument", function() {
+defineGetter(core.Node.prototype, "ownerDocument", function() {
   return this._ownerDocument || null;
 });
 
@@ -114,19 +116,19 @@ core.Node.prototype.isSupported = function(/* string */ feature,
 };
 
 core.Node.prototype._namespaceURI = null;
-core.Node.prototype.__defineGetter__("namespaceURI", function() {
+defineGetter(core.Node.prototype, "namespaceURI", function() {
   return this._namespaceURI || null;
 });
 
-core.Node.prototype.__defineSetter__("namespaceURI", function(value) {
+defineSetter(core.Node.prototype, "namespaceURI", function(value) {
   this._namespaceURI = value;
 });
 
-core.Node.prototype.__defineGetter__("prefix", function() {
+defineGetter(core.Node.prototype, "prefix", function() {
   return this._prefix || null;
 });
 
-core.Node.prototype.__defineSetter__("prefix", function(value) {
+defineSetter(core.Node.prototype, "prefix", function(value) {
 
   if (this.readonly) {
     throw new core.DOMException(core.NO_MODIFICATION_ALLOWED_ERR);
@@ -148,7 +150,7 @@ core.Node.prototype.__defineSetter__("prefix", function(value) {
   this._prefix = value;
 });
 
-core.Node.prototype.__defineGetter__("localName", function() {
+defineGetter(core.Node.prototype, "localName", function() {
   return this._localName || null;
 });
 
@@ -290,14 +292,14 @@ core.NamedNodeMap.prototype.removeNamedItemNS = function(/*string */ namespaceUR
   return found;
 };
 
-core.Attr.prototype.__defineGetter__("ownerElement", function() {
+defineGetter(core.Attr.prototype, "ownerElement", function() {
   return this._ownerElement || null;
 });
 
 
 core.Node.prototype._prefix = false;
 
-core.Node.prototype.__defineSetter__("qualifiedName", function(qualifiedName) {
+defineSetter(core.Node.prototype, "qualifiedName", function(qualifiedName) {
   ns.validate(qualifiedName, this._namespaceURI);
   qualifiedName       = qualifiedName || "";
   this._localName     = qualifiedName.split(":")[1] || null;
@@ -305,7 +307,7 @@ core.Node.prototype.__defineSetter__("qualifiedName", function(qualifiedName) {
   this._nodeName = qualifiedName;
 });
 
-core.Node.prototype.__defineGetter__("qualifiedName", function() {
+defineGetter(core.Node.prototype, "qualifiedName", function() {
   return this._nodeName;
 });
 
@@ -473,15 +475,15 @@ core.Element.prototype.hasAttributeNS = function(/* string */namespaceURI,
   return false;
 };
 
-core.DocumentType.prototype.__defineGetter__("publicId", function() {
+defineGetter(core.DocumentType.prototype, "publicId", function() {
   return this._publicId || "";
 });
 
-core.DocumentType.prototype.__defineGetter__("systemId", function() {
+defineGetter(core.DocumentType.prototype, "systemId", function() {
   return this._systemId || "";
 });
 
-core.DocumentType.prototype.__defineGetter__("internalSubset", function() {
+defineGetter(core.DocumentType.prototype, "internalSubset", function() {
   return this._internalSubset || null;
 });
 
@@ -621,11 +623,11 @@ core.Document.prototype.getElementsByTagNameNS = function(/* String */ namespace
                                                             localName);
 };
 
-core.Element.prototype.__defineSetter__("id", function(id) {
+defineSetter(core.Element.prototype, "id", function(id) {
   this.setAttribute("id", id);
 });
 
-core.Element.prototype.__defineGetter__("id",function() {
+defineGetter(core.Element.prototype, "id", function() {
   return this.getAttribute("id");
 });
 
diff --git a/lib/jsdom/level2/events.js b/lib/jsdom/level2/events.js
index 546a9be608..db44a31237 100644
--- a/lib/jsdom/level2/events.js
+++ b/lib/jsdom/level2/events.js
@@ -4,7 +4,9 @@
  *
  */
 var core = require("./core").dom.level2.core,
-    utils = require("../utils");
+    utils = require("../utils"),
+    defineGetter = utils.defineGetter,
+    defineSetter = utils.defineSetter;
 
 // modify cloned instance for more info check: https://github.com/tmpvar/jsdom/issues/325
 core = Object.create(core);
@@ -378,10 +380,10 @@ function dispatchAttrEvent(change) {
 utils.intercept(core.AttrNodeMap, 'removeNamedItem', dispatchAttrEvent('REMOVAL'));
 utils.intercept(core.AttrNodeMap, 'setNamedItem', dispatchAttrEvent('ADDITION'));
 
-core.CharacterData.prototype.__defineGetter__("_nodeValue", function() {
+defineGetter(core.CharacterData.prototype, "_nodeValue", function() {
   return this.__nodeValue;
 });
-core.CharacterData.prototype.__defineSetter__("_nodeValue", function(value) {
+defineSetter(core.CharacterData.prototype, "_nodeValue", function(value) {
   var oldValue = this.__nodeValue;
   this.__nodeValue = value;
   if (this._ownerDocument && this._parentNode && mutationEventsEnabled(this)) {
diff --git a/lib/jsdom/level2/html.js b/lib/jsdom/level2/html.js
index 964c3da705..1673156671 100644
--- a/lib/jsdom/level2/html.js
+++ b/lib/jsdom/level2/html.js
@@ -1,6 +1,8 @@
 var core                  = require("./core").dom.level2.core,
     events                = require("./core").dom.level2.events,
     applyDocumentFeatures = require('../browser/documentfeatures').applyDocumentFeatures,
+    defineGetter          = require('../utils').defineGetter,
+    defineSetter          = require('../utils').defineSetter,
     URL                   = require("url"),
     Path                  = require('path'),
     fs                    = require("fs"),
@@ -194,7 +196,7 @@ function define(elementClass, def) {
         attr = n.attr || prop.toLowerCase();
 
       if (!n.prop || n.read !== false) {
-        elem.prototype.__defineGetter__(prop, function() {
+        defineGetter(elem.prototype, prop, function() {
           var s = this.getAttribute(attr);
           if (n.type && n.type === 'boolean') {
             return s !== null;
@@ -210,7 +212,7 @@ function define(elementClass, def) {
       }
 
       if (!n.prop || n.write !== false) {
-        elem.prototype.__defineSetter__(prop, function(val) {
+        defineSetter(elem.prototype, prop, function(val) {
           if (!val) {
             this.removeAttribute(attr);
           }
@@ -729,10 +731,10 @@ define('HTMLBodyElement', {
      'onfocus', 'onhashchange', 'onload', 'onmessage', 'onoffline', 'ononline',
      'onpagehide', 'onpageshow', 'onpopstate', 'onresize', 'onscroll',
      'onstorage', 'onunload'].forEach(function (name) {
-      proto.__defineSetter__(name, function (handler) {
+      defineSetter(proto, name, function (handler) {
         this._ownerDocument.parentWindow[name] = handler;
       });
-      proto.__defineGetter__(name, function () {
+      defineGetter(proto, name, function () {
         return this._ownerDocument.parentWindow[name];
       });
     });
@@ -1862,7 +1864,7 @@ define('HTMLFrameElement', {
     var parent = this._ownerDocument.parentWindow;
     var frameID = parent._length++;
     var self = this;
-    parent.__defineGetter__(frameID, function () {
+    defineGetter(parent, frameID, function () {
       return self.contentWindow;
     });
 
diff --git a/lib/jsdom/level2/style.js b/lib/jsdom/level2/style.js
index bb957376c1..53ff6e4d03 100644
--- a/lib/jsdom/level2/style.js
+++ b/lib/jsdom/level2/style.js
@@ -1,6 +1,8 @@
 var core = require("./core").dom.level2.core,
     html = require("./html").dom.level2.html,
     utils = require("../utils"),
+    defineGetter = utils.defineGetter,
+    defineSetter = utils.defineSetter,
     cssom = require("cssom"),
     cssstyle = require("cssstyle"),
     assert = require('assert');
@@ -76,7 +78,7 @@ core.StyleSheetList.prototype = {
   }
 };
 
-core.Document.prototype.__defineGetter__('styleSheets', function() {
+defineGetter(core.Document.prototype, 'styleSheets', function() {
   if (!this._styleSheets) {
     this._styleSheets = new core.StyleSheetList();
   }
@@ -183,7 +185,7 @@ utils.intercept(core.AttrNodeMap, 'setNamedItem', function(_super, args, attr) {
 /**
  * Lazily create a CSSStyleDeclaration.
  */
-html.HTMLElement.prototype.__defineGetter__('style', function() {
+defineGetter(html.HTMLElement.prototype, 'style', function() {
   if (typeof this._style === 'string') {
     // currently, cssom's parse doesn't really work if you pass in
     // {state: 'name'}, so instead we just build a dummy sheet.
@@ -237,7 +239,7 @@ var getOrCreateSheet = function() {
   }
   return this._cssStyleSheet;
 };
-html.HTMLLinkElement.prototype.__defineGetter__('sheet', getOrCreateSheet);
+defineGetter(html.HTMLLinkElement.prototype, 'sheet', getOrCreateSheet);
 
 assert.equal(undefined, html.HTMLStyleElement._init);
 html.HTMLStyleElement._init = function() {
@@ -258,7 +260,7 @@ html.HTMLStyleElement._init = function() {
     evaluateStylesheet.call(this, content, this.sheet, this._ownerDocument.URL);
   });
 };
-html.HTMLStyleElement.prototype.__defineGetter__('sheet', getOrCreateSheet);
+defineGetter(html.HTMLStyleElement.prototype, 'sheet', getOrCreateSheet);
 
 exports.dom = {
   level2 : {
diff --git a/lib/jsdom/level3/core.js b/lib/jsdom/level3/core.js
index c9221e7da3..495dbc79e2 100644
--- a/lib/jsdom/level3/core.js
+++ b/lib/jsdom/level3/core.js
@@ -1,4 +1,6 @@
 var core          = require("../level2/core").dom.level2.core,
+    defineGetter  = require('../utils').defineGetter,
+    defineSetter  = require('../utils').defineSetter,
     HtmlToDom     = require('../browser/htmltodom').HtmlToDom,
     domToHtml     = require('../browser/domtohtml').domToHtml,
     htmlencoding  = require('../browser/htmlencoding'),
@@ -149,7 +151,7 @@ core.Node.prototype.isSameNode = function(other) {
 };
 
 // @see http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/core.html#Node3-textContent
-core.Node.prototype.__defineGetter__('textContent', function() {
+defineGetter(core.Node.prototype, 'textContent', function() {
   switch (this.nodeType) {
     case this.COMMENT_NODE:
     case this.CDATA_SECTION_NODE:
@@ -176,7 +178,7 @@ core.Node.prototype.__defineGetter__('textContent', function() {
   }
 });
 
-core.Node.prototype.__defineSetter__('textContent', function(txt) {
+defineSetter(core.Node.prototype, 'textContent', function(txt) {
   for (var i = this.childNodes.length; --i >=0;) {
     this.removeChild(this.childNodes.item(i));
   }
@@ -326,7 +328,7 @@ core.Node.prototype.getUserData = function(key) {
 
 */
     // Introduced in DOM Level 3:
-core.Attr.prototype.__defineGetter__('isId', function() {
+defineGetter(core.Attr.prototype, 'isId', function() {
   return (this.name.toLowerCase() === 'id');
 });
 /*
@@ -446,22 +448,22 @@ core.DOMError.prototype = {};
 core.DOMError.prototype.SEVERITY_WARNING     = 1;
 core.DOMError.prototype.SEVERITY_ERROR       = 2;
 core.DOMError.prototype.SEVERITY_FATAL_ERROR = 3;
-core.DOMError.prototype.__defineGetter__('severity', function() {
+defineGetter(core.DOMError.prototype, 'severity', function() {
   return this._severity;
 });
-core.DOMError.prototype.__defineGetter__('message', function() {
+defineGetter(core.DOMError.prototype, 'message', function() {
   return this._message;
 });
-core.DOMError.prototype.__defineGetter__('type', function() {
+defineGetter(core.DOMError.prototype, 'type', function() {
   return this._type;
 });
-core.DOMError.prototype.__defineGetter__('relatedException', function() {
+defineGetter(core.DOMError.prototype, 'relatedException', function() {
   return this._relatedException;
 });
-core.DOMError.prototype.__defineGetter__('relatedData', function() {
+defineGetter(core.DOMError.prototype, 'relatedData', function() {
   return this._relatedData;
 });
-core.DOMError.prototype.__defineGetter__('location', function() {
+defineGetter(core.DOMError.prototype, 'location', function() {
   return this._location;
 });
 
@@ -514,7 +516,7 @@ core.DOMConfiguration.prototype = {
 };
 
 //core.Document.prototype._domConfig = new core.DOMConfiguration();
-core.Document.prototype.__defineGetter__('domConfig', function() {
+defineGetter(core.Document.prototype, 'domConfig', function() {
   return this._domConfig || new core.DOMConfiguration();;
 });
 
@@ -615,7 +617,7 @@ core.DOMStringList.prototype = {
 
 // Introduced in DOM Level 3:
 core.Document.prototype._inputEncoding = null;
-core.Document.prototype.__defineGetter__('inputEncoding', function() {
+defineGetter(core.Document.prototype, 'inputEncoding', function() {
   return this._inputEncoding;
 });
 /*