diff --git a/mithril.js b/mithril.js
index 5a4eb7ae..f5812eef 100644
--- a/mithril.js
+++ b/mithril.js
@@ -23,7 +23,7 @@ Mithril = m = new function app(window, undefined) {
 	 */
 	function m() {
 		var args = [].slice.call(arguments)
-		var hasAttrs = args[1] != null && isObj(args[1]) && !("tag" in args[1]) && !("subtree" in args[1])
+		var hasAttrs = isObj(args[1]) && !("tag" in args[1]) && !("subtree" in args[1])
 		var attrs = hasAttrs ? args[1] : {}
 		var classAttrName = "class" in attrs ? "class" : "className"
 		var cell = {tag: "div", attrs: {}}
@@ -143,20 +143,20 @@ Mithril = m = new function app(window, undefined) {
 					if (change.action == INSERTION) {
 						var dummy = window.document.createElement("div")
 						dummy.key = data[change.index].attrs.key
-						parentElement.insertBefore(dummy, parentElement.childNodes[change.index])
+						parentElement.insertBefore(dummy, parentElement.childNodes[change.index] || null)
 						newCached.splice(change.index, 0, {attrs: {key: data[change.index].attrs.key}, nodes: [dummy]})
 					}
 
 					if (change.action == MOVE) {
 						if (parentElement.childNodes[change.index] !== change.element && change.element !== null) {
-							parentElement.insertBefore(change.element, parentElement.childNodes[change.index])
+							parentElement.insertBefore(change.element, parentElement.childNodes[change.index] || null)
 						}
 						newCached[change.index] = cached[change.from]
 					}
 				}
 				for (var i = 0; i < unkeyed.length; i++) {
 					var change = unkeyed[i]
-					parentElement.insertBefore(change.element, parentElement.childNodes[change.index])
+					parentElement.insertBefore(change.element, parentElement.childNodes[change.index] || null)
 					newCached[change.index] = cached[change.index]
 				}
 				cached = newCached
@@ -352,7 +352,7 @@ Mithril = m = new function app(window, undefined) {
 			var isElement = nextSibling.nodeType != 1
 			var placeholder = window.document.createElement("span")
 			if (isElement) {
-				parentElement.insertBefore(placeholder, nextSibling)
+				parentElement.insertBefore(placeholder, nextSibling || null)
 				placeholder.insertAdjacentHTML("beforebegin", data)
 				parentElement.removeChild(placeholder)
 			}
@@ -810,8 +810,8 @@ Mithril = m = new function app(window, undefined) {
 		if (options.dataType && options.dataType.toLowerCase() === "jsonp") {
 			var callbackKey = "mithril_callback_" + new Date().getTime() + "_" + (Math.round(Math.random() * 1e16)).toString(36)
 			var script = window.document.createElement("script")
-
-			window[callbackKey] = function(resp){
+			
+			window[callbackKey] = function(resp) {
 				window.document.body.removeChild(script)
 				options.onload({
 					type: "load",
@@ -819,11 +819,10 @@ Mithril = m = new function app(window, undefined) {
 						responseText: resp
 					}
 				})
-				delete window[callbackKey]
+				window[callbackKey] = undefined
 			}
 
 			script.onerror = function(e) {
-				delete window[callbackKey]
 				window.document.body.removeChild(script)
 
 				options.onerror({
@@ -833,6 +832,7 @@ Mithril = m = new function app(window, undefined) {
 						responseText: JSON.stringify({error: "Error making jsonp request"})
 					}
 				})
+				window[callbackKey] = undefined
 
 				return false
 			}
diff --git a/tests/mithril-tests.js b/tests/mithril-tests.js
index 75443038..e3e6bd3e 100644
--- a/tests/mithril-tests.js
+++ b/tests/mithril-tests.js
@@ -1,6 +1,6 @@
 function testMithril(mock) {
 	m.deps(mock)
-
+	
 	//m
 	test(function() {return m("div").tag === "div"})
 	test(function() {return m(".foo").tag === "div"})
@@ -1664,136 +1664,91 @@ function testMithril(mock) {
 	// m.request over jsonp
 	test(function(){
 		// script tags cannot be appended directly on the document
+		var body = mock.document.createElement("body")
+		mock.document.body = body
+		mock.document.appendChild(body)
+
+		var	error = m.prop("no error")
+		var data
+		var req = m.request({url: "/test", dataType: "jsonp"}).then(function(received) {data = received}, error)
+		var callbackKey = Object.keys(mock).filter(function(globalKey){
+			return globalKey.indexOf("mithril_callback") > -1
+		}).pop()
+		var scriptTag = [].slice.call(mock.document.getElementsByTagName("script")).filter(function(script){
+			return script.src.indexOf(callbackKey) > -1
+		}).pop()
+		mock[callbackKey]({foo: "bar"})
+		mock.document.removeChild(body)
+		return scriptTag.src.indexOf("/test?callback=mithril_callback") > -1 && data.foo == "bar"
+	})
+	test(function(){
+		// script tags cannot be appended directly on the document
+		var body = mock.document.createElement("body")
+		mock.document.body = body
+		mock.document.appendChild(body)
+
+		var	error = m.prop("no error")
+		var data
+		var req = m.request({url: "/test", dataType: "jsonp", callbackKey: "jsonpCallback"}).then(function(received) {data = received}, error);
+		var callbackKey = Object.keys(mock).filter(function(globalKey){
+			return globalKey.indexOf("mithril_callback") > -1
+		}).pop()
+		var scriptTag = [].slice.call(mock.document.getElementsByTagName("script")).filter(function(script){
+			return script.src.indexOf(callbackKey) > -1
+		}).pop()
+		mock[callbackKey]({foo: "bar1"})
+		mock.document.removeChild(body)
+		return scriptTag.src.indexOf("/test?jsonpCallback=mithril_callback") > -1 && data.foo == "bar1"
+	})
+	test(function(){
+		var body = mock.document.createElement("body")
+		mock.document.body = body
+		mock.document.appendChild(body)
+
+		var req = m.request({url: "/test", dataType: "jsonp"})
+		var callbackKey = Object.keys(mock).filter(function(globalKey){
+			return globalKey.indexOf("mithril_callback") > -1
+		}).pop()
+		var scriptTag = [].slice.call(mock.document.getElementsByTagName("script")).filter(function(script){
+			return script.src.indexOf(callbackKey) > -1
+		}).pop();
+		mock[callbackKey]({foo: "bar1"})
+		var out = {foo: "bar1"}
+		mock.document.removeChild(body)
+		return JSON.stringify(out) === JSON.stringify(req())
+	})
+	test(function(){
+		var body = mock.document.createElement("body")
+		mock.document.body = body
+		mock.document.appendChild(body)
+
+		var req = m.request({url: "/test", dataType: "jsonp", data: {foo: "bar"}})
+		var callbackKey = Object.keys(mock).filter(function(globalKey){
+			return globalKey.indexOf("mithril_callback") > -1
+		}).pop()
+		var scriptTag = [].slice.call(mock.document.getElementsByTagName("script")).filter(function(script){
+			return script.src.indexOf(callbackKey) > -1
+		}).pop();
+		mock[callbackKey]({foo: "bar"})
+		return scriptTag.src.indexOf("foo=bar") > -1
+	})
+	test(function(){
 		var body = mock.document.createElement("body");
 		mock.document.body = body;
 		mock.document.appendChild(body);
 
-		var	error = m.prop("no error");
-		var data
-		var req = m.request({url: "/test", dataType: "jsonp"}).then(function(received) {data = received}, error);
+		var _window = mock;
+		var error = m.prop(false);
+		var req = m.request({url: "/test", dataType: "jsonp", method: "GET", data: {foo: "bar"}});
 		var callbackKey = Object.keys(mock).filter(function(globalKey){
 			return globalKey.indexOf("mithril_callback") > -1
-		}).pop();
+		}).pop()
 		var scriptTag = [].slice.call(mock.document.getElementsByTagName("script")).filter(function(script){
 			return script.src.indexOf(callbackKey) > -1
 		}).pop();
 		mock[callbackKey]({foo: "bar"})
 		mock.document.removeChild(body);
-		return scriptTag.src.indexOf("/test?callback=mithril_callback") > -1 && data.foo == "bar";
-	})
-	test(function(){
-		// script tags cannot be appended directly on the document
-		var body = mock.document.createElement("body");
-		mock.document.body = body;
-		mock.document.appendChild(body);
-
-		var	error = m.prop("no error");
-		var data
-		var req = m.request({url: "/test", dataType: "jsonp", callbackKey: "jsonpCallback"}).then(function(received) {data = received}, error);
-		var callbackKey = Object.keys(mock).filter(function(globalKey){
-			return globalKey.indexOf("mithril_callback") > -1
-		}).pop();
-		var scriptTag = [].slice.call(mock.document.getElementsByTagName("script")).filter(function(script){
-			return script.src.indexOf(callbackKey) > -1
-		}).pop();
-		mock[callbackKey]({foo: "bar1"})//fixme ie
-		mock.document.removeChild(body);
-		return scriptTag.src.indexOf("/test?jsonpCallback=mithril_callback") > -1 && data.foo == "bar1";
-	})
-	test(function(){
-		var body = mock.document.createElement("body");
-		mock.document.body = body;
-		mock.document.appendChild(body);
-
-		var _window = mock;
-		var req = m.request({
-			url: "/test",
-			dataType: "jsonp",
-			background: true
-		});
-		var callbackKeys = [];
-		Object.keys(_window).forEach(function(globalKey){
-			if(globalKey.indexOf("mithril_callback") > -1)
-				callbackKeys.push(globalKey);
-		});
-		var scriptTag = null;
-		mock.document.getElementsByTagName("script").forEach(function(script){
-			if(!scriptTag && script.src.indexOf(callbackKeys[0]) > -1)
-				scriptTag = script;
-		});
-		var out = { foo: "bar" };
-		if(scriptTag && callbackKeys.length > 0){
-			_window[callbackKeys[0]](out);
-			mock.document.body.removeChild(scriptTag);
-			delete _window[callbackKeys[0]];
-		}
-		mock.document.removeChild(body);
-		return JSON.stringify(out) === JSON.stringify(req());
-	})
-	test(function(){
-		var body = mock.document.createElement("body");
-		mock.document.body = body;
-		mock.document.appendChild(body);
-
-		var _window = mock;
-		var error = m.prop(false);
-		var req = m.request({
-			url: "/test",
-			dataType: "jsonp",
-			data: { foo: "bar" },
-			background: true
-		});
-		var callbackKeys = [];
-		Object.keys(_window).forEach(function(globalKey){
-			if(globalKey.indexOf("mithril_callback") > -1)
-				callbackKeys.push(globalKey);
-		});
-		var scriptTag = null;
-		mock.document.getElementsByTagName("script").forEach(function(script){
-			if(!scriptTag && script.src.indexOf(callbackKeys[0]) > -1)
-				scriptTag = script;
-		});
-		var correctData = false;
-		if(scriptTag){
-			correctData = scriptTag.src.indexOf("foo=bar") > -1;
-			mock.document.body.removeChild(scriptTag);
-			delete _window[callbackKeys[0]];
-		}
-		mock.document.removeChild(body);
-		return correctData;
-	})
-	test(function(){
-		var body = mock.document.createElement("body");
-		mock.document.body = body;
-		mock.document.appendChild(body);
-
-		var _window = mock;
-		var error = m.prop(false);
-		var req = m.request({
-			url: "/test",
-			dataType: "jsonp",
-			method: "GET",
-			data: { foo: "bar" },
-			background: true
-		});
-		var callbackKeys = [];
-		Object.keys(_window).forEach(function(globalKey){
-			if(globalKey.indexOf("mithril_callback") > -1)
-				callbackKeys.push(globalKey);
-		});
-		var scriptTag = null;
-		mock.document.getElementsByTagName("script").forEach(function(script){
-			if(!scriptTag && script.src.indexOf(callbackKeys[0]) > -1)
-				scriptTag = script;
-		});
-		var correctData = false;
-		if(scriptTag){
-			correctData = scriptTag.src.match(/foo=bar/g).length == 1;
-			mock.document.body.removeChild(scriptTag);
-			delete _window[callbackKeys[0]];
-		}
-		mock.document.removeChild(body);
-		return correctData;
+		return scriptTag.src.match(/foo=bar/g).length == 1;
 	})
 
 	//m.deferred
@@ -2000,10 +1955,9 @@ function testMithril(mock) {
 	test(function() {
 		mock.requestAnimationFrame.$resolve()
 
-		var controller
 		var root = mock.document.createElement("div")
-		m.module(root, {
-			controller: function() {controller = this},
+		var controller = m.module(root, {
+			controller: function() {},
 			view: function(ctrl) {return ctrl.value}
 		})
 
@@ -2013,7 +1967,6 @@ function testMithril(mock) {
 		controller.value = "foo"
 		m.endComputation()
 		mock.requestAnimationFrame.$resolve()
-
 		return root.childNodes[0].nodeValue === "foo"
 	})