diff --git a/lib/frame.js b/lib/frame.js
index de73007..ac7f80a 100644
--- a/lib/frame.js
+++ b/lib/frame.js
@@ -11,6 +11,7 @@
 	const {check: originalCheck, checkStack: originalCheckStack} = require("./check");
 	const {getWrapped} = require("./modifiedAPIFunctions");
 	const extension = require("./extension");
+	const iframeProtection = require("./iframeProtection");
 	
 	const logging = require("./logging");
 	const {error, warning, message, notice, verbose, setPrefix: setLogPrefix} = logging;
@@ -149,41 +150,16 @@
 			{check, checkStack, ask: askWrapper, notify, prefs}
 		);
 		message("prepare to intercept (i)frames.");
-
-		[window.HTMLIFrameElement, window.HTMLFrameElement].forEach(function(constructor){
-			var oldContentWindowGetter = constructor.prototype.__lookupGetter__("contentWindow");
-			Object.defineProperty(
-				getWrapped(constructor.prototype),
-				"contentWindow",
-				{
-					enumerable: true,
-					configurable: true,
-					get: exportFunction(function(){
-						var window = oldContentWindowGetter.call(this);
-						if (window){
-							interceptWindow(window);
-						}
-						return window;
-					}, window)
+		
+		function interceptAllFrames(){
+			const currentLength = window.length;
+			for (let i = currentLength; i--;){
+				if (!interceptedWindows.get(wrappedWindow[i])){
+					interceptWindow(window[i]);
 				}
-			);
-			var oldContentDocumentGetter = constructor.prototype.__lookupGetter__("contentDocument");
-			Object.defineProperty(
-				getWrapped(constructor.prototype),
-				"contentDocument",
-				{
-					enumerable: true,
-					configurable: true,
-					get: exportFunction(function(){
-						var document = oldContentDocumentGetter.call(this);
-						if (document){
-							interceptWindow(document.defaultView);
-						}
-						return document;
-					}, window)
-				}
-			);
-		});
+			}
+		}
+		iframeProtection.protect(window, wrappedWindow, interceptWindow, interceptAllFrames);
 		
 		const matchMediaDescriptor = Object.getOwnPropertyDescriptor(wrappedWindow, "matchMedia");
 		const originalMatchMedia = matchMediaDescriptor.value;
diff --git a/lib/iframeProtection.js b/lib/iframeProtection.js
new file mode 100644
index 0000000..874178a
--- /dev/null
+++ b/lib/iframeProtection.js
@@ -0,0 +1,150 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+(function(){
+	"use strict";
+	
+	let scope;
+	if ((typeof exports) !== "undefined"){
+		scope = exports;
+	}
+	else {
+		scope = require.register("./iframeProtection", {});
+	}
+	const {getWrapped} = require("./modifiedAPIFunctions");
+	
+	scope.protect = function protect(window, wrappedWindow, singleCallback, allCallback){
+		
+
+		[window.HTMLIFrameElement, window.HTMLFrameElement].forEach(function(constructor){
+			var oldContentWindowGetter = constructor.prototype.__lookupGetter__("contentWindow");
+			Object.defineProperty(
+				getWrapped(constructor.prototype),
+				"contentWindow",
+				{
+					enumerable: true,
+					configurable: true,
+					get: exportFunction(function(){
+						var window = oldContentWindowGetter.call(this);
+						if (window){
+							singleCallback(window);
+						}
+						return window;
+					}, window)
+				}
+			);
+			var oldContentDocumentGetter = constructor.prototype.__lookupGetter__("contentDocument");
+			Object.defineProperty(
+				getWrapped(constructor.prototype),
+				"contentDocument",
+				{
+					enumerable: true,
+					configurable: true,
+					get: exportFunction(function(){
+						var document = oldContentDocumentGetter.call(this);
+						if (document){
+							singleCallback(document.defaultView);
+						}
+						return document;
+					}, window)
+				}
+			);
+		});
+		[
+			// useless as length could be obtained before the iframe is created and window.frames === window
+			// {
+			// 	object: wrappedWindow,
+			// 	methods: [],
+			// 	getters: ["length", "frames"],
+			// 	setters: []
+			// },
+			{
+				object: wrappedWindow.Node.prototype,
+				methods: ["appendChild", "insertBefore", "replaceChild"],
+				getters: [],
+				setters: []
+			},
+			{
+				object: wrappedWindow.Element.prototype,
+				methods: [
+					"append", "prepend",
+					"insertAdjacentElement", "insertAdjacentHTML", "insertAdjacentText",
+					"replaceWith"
+				],
+				getters: [],
+				setters: ["innerHTML", "outerHTML"]
+			}
+		].forEach(function(protectionDefinition){
+			const object = protectionDefinition.object;
+			protectionDefinition.methods.forEach(function(method){
+				const descriptor = Object.getOwnPropertyDescriptor(object, method);
+				const original = descriptor.value;
+				descriptor.value = exportFunction(eval(`(function ${method}(){
+					const value = arguments.length?
+						original.apply(this, window.Array.from(arguments)):
+						original.call(this);
+					allCallback();
+					return value;
+				})`), window);
+				Object.defineProperty(object, method, descriptor);
+			});
+			protectionDefinition.getters.forEach(function(property){
+				const descriptor = Object.getOwnPropertyDescriptor(object, property);
+				const temp = eval(`({
+					get ${property}(){
+						const ret = this.${property};
+						allCallback();
+						return ret;
+					}
+				})`);
+				descriptor.get = exportFunction(Object.getOwnPropertyDescriptor(temp, property).get, window);
+				Object.defineProperty(object, property, descriptor);
+			});
+			protectionDefinition.setters.forEach(function(property){
+				const descriptor = Object.getOwnPropertyDescriptor(object, property);
+				const temp = eval(`({
+					set ${property}(value){
+						const ret = this.${property} = value;
+						allCallback();
+						return ret;
+					}
+				})`);
+				descriptor.set = exportFunction(Object.getOwnPropertyDescriptor(temp, property).set, window);
+				Object.defineProperty(object, property, descriptor);
+			});
+		});
+		
+		// MutationObserver to intercept iframes while generating the DOM.
+		var observer = new MutationObserver(allCallback);
+		observer.observe(window.document.documentElement, {subtree: true, childList: true});
+		window.document.addEventListener("DOMContentLoaded", function(){
+			observer.disconnect();
+		});
+		
+		// MutationObserver does not trigger fast enough when document.write is used
+		const documentWriteDescriptor = Object.getOwnPropertyDescriptor(wrappedWindow.HTMLDocument.prototype, "write");
+		const documentWrite = documentWriteDescriptor.value;
+		documentWriteDescriptor.value = exportFunction(function write(str){
+			const parts = str.split(/(?=>)/);
+			const length = parts.length;
+			for (let i = 0; i < length; i += 1){
+				documentWrite.call(this, parts[i]);
+				allCallback();
+			}
+		}, window);
+		Object.defineProperty(wrappedWindow.HTMLDocument.prototype, "write", documentWriteDescriptor);
+		
+		const documentWritelnDescriptor = Object.getOwnPropertyDescriptor(wrappedWindow.HTMLDocument.prototype, "writeln");
+		const documentWriteln = documentWritelnDescriptor.value;
+		documentWritelnDescriptor.value = exportFunction(function writeln(str){
+			const parts = str.split(/(?=>)/);
+			const length = parts.length - 1;
+			for (let i = 0; i < length; i += 1){
+				documentWrite.call(this, parts[i]);
+				allCallback();
+			}
+			documentWriteln.call(this, parts[length]);
+		}, window);
+		Object.defineProperty(wrappedWindow.HTMLDocument.prototype, "writeln", documentWritelnDescriptor);
+	};
+}());
\ No newline at end of file
diff --git a/manifest.json b/manifest.json
index 2644e6c..7ec5a19 100644
--- a/manifest.json
+++ b/manifest.json
@@ -58,6 +58,7 @@
 			
 			"lib/lists.js",
 			"lib/check.js",
+			"lib/iframeProtection.js",
 			
 			"lib/frame.js"
 		]
diff --git a/releaseNotes.txt b/releaseNotes.txt
index b096ee2..b461ef0 100644
--- a/releaseNotes.txt
+++ b/releaseNotes.txt
@@ -27,6 +27,7 @@ Version 0.5.9:
 		- preventing double interception (increased performance and reduced detectability)
 		- detection over navigator and DOMRect getters was possible
 		- audio cache could break readout
+		- improved iFrame protection
 	
 	known issues:
 		- if a data URL is blocked the page action button does not appear