diff --git a/README.md b/README.md
index fb4ef543..83cfae97 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ Mithril's `config` method is now replaced by several lifecycle methods to improv
 
 ## Robustness
 
-There are over 2600 assertions in the test suite, and tests cover even difficult-to-test things like `location.href`, `element.innerHTML` and `XMLHttpRequest` usage.
+There are over 2700 assertions in the test suite, and tests cover even difficult-to-test things like `location.href`, `element.innerHTML` and `XMLHttpRequest` usage.
 
 ## Modularity
 
diff --git a/api/tests/index.html b/api/tests/index.html
index 649829c9..cd27120d 100644
--- a/api/tests/index.html
+++ b/api/tests/index.html
@@ -11,6 +11,7 @@
 		<script src="../../test-utils/domMock.js"></script>
 		<script src="../../test-utils/pushStateMock.js"></script>
 
+		<script src="../../util/stream.js"></script>
 		<script src="../../render/node.js"></script>
 		<script src="../../render/trust.js"></script>
 		<script src="../../render/hyperscript.js"></script>
diff --git a/api/tests/test-router.js b/api/tests/test-router.js
index 832488e7..2c2dd8de 100644
--- a/api/tests/test-router.js
+++ b/api/tests/test-router.js
@@ -1,6 +1,7 @@
 "use strict"
 
 var o = require("../../ospec/ospec")
+var callAsync = require("../../test-utils/callAsync")
 var pushStateMock = require("../../test-utils/pushStateMock")
 var domMock = require("../../test-utils/domMock")
 
@@ -28,7 +29,7 @@ o.spec("route", function() {
 		route = apiRouter($window, coreRenderer($window), redraw)
 	})
 
-	o("renders into `root`", function() {
+	o("renders into `root`", function(done) {
 		route(root, "/", {
 			"/" : {
 				view: function() {
@@ -37,7 +38,11 @@ o.spec("route", function() {
 			}
 		})
 
-		o(root.firstChild.nodeName).equals("DIV")
+		callAsync(function() {
+			o(root.firstChild.nodeName).equals("DIV")
+			
+			done()
+		})
 	})
 
 	o("redraws when render function is executed", function(done) {
@@ -55,19 +60,21 @@ o.spec("route", function() {
 			}
 		})
 
-		o(oninit.callCount).equals(1)
+		callAsync(function() {
+			o(oninit.callCount).equals(1)
 
-		redraw.publish()
+			redraw.publish()
 
-		// Wrapped to give time for the rate-limited redraw to fire
-		setTimeout(function() {
-			o(onupdate.callCount).equals(1)
+			// Wrapped to give time for the rate-limited redraw to fire
+			setTimeout(function() {
+				o(onupdate.callCount).equals(1)
 
-			done()
-		}, FRAME_BUDGET)
+				done()
+			}, FRAME_BUDGET)
+		})
 	})
 
-	o("redraws on events", function(done, timeout) {
+	o("redraws on events", function(done) {
 		var onupdate = o.spy()
 		var oninit   = o.spy()
 		var onclick  = o.spy()
@@ -87,21 +94,23 @@ o.spec("route", function() {
 			}
 		})
 
-		root.firstChild.dispatchEvent(e)
+		callAsync(function() {
+			root.firstChild.dispatchEvent(e)
 
-		o(oninit.callCount).equals(1)
+			o(oninit.callCount).equals(1)
 
-		o(onclick.callCount).equals(1)
-		o(onclick.this).equals(root.firstChild)
-		o(onclick.args[0].type).equals("click")
-		o(onclick.args[0].target).equals(root.firstChild)
+			o(onclick.callCount).equals(1)
+			o(onclick.this).equals(root.firstChild)
+			o(onclick.args[0].type).equals("click")
+			o(onclick.args[0].target).equals(root.firstChild)
 
-		// Wrapped to give time for the rate-limited redraw to fire
-		setTimeout(function() {
-			o(onupdate.callCount).equals(1)
+			// Wrapped to give time for the rate-limited redraw to fire
+			setTimeout(function() {
+				o(onupdate.callCount).equals(1)
 
-			done()
-		}, FRAME_BUDGET)
+				done()
+			}, FRAME_BUDGET)
+		})
 	})
 
 	o("event handlers can skip redraw", function(done) {
@@ -126,19 +135,21 @@ o.spec("route", function() {
 			}
 		})
 
-		root.firstChild.dispatchEvent(e)
+		callAsync(function() {
+			root.firstChild.dispatchEvent(e)
 
-		o(oninit.callCount).equals(1)
+			o(oninit.callCount).equals(1)
 
-		// Wrapped to ensure no redraw fired
-		setTimeout(function() {
-			o(onupdate.callCount).equals(0)
+			// Wrapped to ensure no redraw fired
+			setTimeout(function() {
+				o(onupdate.callCount).equals(0)
 
-			done()
-		}, FRAME_BUDGET)
+				done()
+			}, FRAME_BUDGET)
+		})
 	})
 
-	o("changes location on route.link", function() {
+	o("changes location on route.link", function(done) {
 		var e = $window.document.createEvent("MouseEvents")
 
 		e.initEvent("click", true, true)
@@ -161,10 +172,14 @@ o.spec("route", function() {
 			}
 		})
 
-		o($window.location.href).equals("http://localhost/?/")
+		callAsync(function() {
+			o($window.location.href).equals("http://localhost/?/")
 
-		root.firstChild.dispatchEvent(e)
+			root.firstChild.dispatchEvent(e)
 
-		o($window.location.href).equals("http://localhost/?/test")
+			o($window.location.href).equals("http://localhost/?/test")
+			
+			done()
+		})
 	})
 })
diff --git a/mithril.js b/mithril.js
index 26485e13..2b53fefe 100644
--- a/mithril.js
+++ b/mithril.js
@@ -16,8 +16,8 @@ function initStream(stream, args) {
 	stream.constructor = createStream
 	stream._state = {id: guid++, value: undefined, error: undefined, state: 0, derive: undefined, recover: undefined, deps: {}, parents: [], errorStream: undefined, endStream: undefined}
 	stream.map = map, stream.ap = ap, stream.of = createStream
-	stream.valueOf = valueOf
-	stream.catch = doCatch
+	stream.valueOf = valueOf, stream.toJSON = toJSON
+	stream.run = run, stream.catch = doCatch
 	
 	Object.defineProperties(stream, {
 		error: {get: function() {
@@ -46,15 +46,18 @@ function initStream(stream, args) {
 	})
 }
 function updateStream(stream, value, error) {
-	if (!absorbStream(stream, value, false) && !absorbStream(stream, error, true)) {
-		updateState(stream, value, error)
-		for (var id in stream._state.deps) updateDependency(stream._state.deps[id], false)
-		finalize(stream)
-	}
+	updateState(stream, value, error)
+	for (var id in stream._state.deps) updateDependency(stream._state.deps[id], false)
+	finalize(stream)
 }
 function updateState(stream, value, error) {
+	error = unwrapError(value, error)
 	if (error !== undefined && typeof stream._state.recover === "function") {
-		try {updateValues(stream, stream._state.recover(), undefined)}
+		try {
+			var recovered = stream._state.recover()
+			if (recovered === HALT) return
+			updateValues(stream, recovered, undefined)
+		}
 		catch (e) {updateValues(stream, undefined, e)}
 	}
 	else updateValues(stream, value, error)
@@ -73,7 +76,8 @@ function updateDependency(stream, mustSync) {
 		else {
 			try {
 				var value = state.derive()
-				if (!absorbStream(stream, value)) updateState(stream, value, undefined)
+				if (value === HALT) return
+				updateState(stream, value, undefined)
 			}
 			catch (e) {
 				updateState(stream, undefined, e)
@@ -81,29 +85,28 @@ function updateDependency(stream, mustSync) {
 		}
 	}
 }
-function absorbStream(stream, value, isError) {
+function unwrapError(value, error) {
 	if (value != null && value.constructor === createStream) {
-		if (value._state.state === 2) {
-			stream.end(true)
-			stream(value())
-		}
-		else if (value._state.error) stream.error(value.error())
-		else if (value._state.state === 0) return true
-		else if (!isError) stream(value())
-		else stream.error(value())
-		return true
+		if (value._state.error !== undefined) error = value._state.error
+		else error = unwrapError(value._state.value, value._state.error)
 	}
-	return false
+	return error
 }
 function finalize(stream) {
 	stream._state.changed = false
 	for (var id in stream._state.deps) stream._state.deps[id]._state.changed = false
 }
+function run(fn) {
+	var self = createStream(), stream = this
+	return initDependency(self, [stream], function() {
+		return absorb(self, fn(stream()))
+	}, undefined)
+}
 function doCatch(fn) {
-	var stream = this
+	var self = createStream(), stream = this
 	var derive = function() {return stream._state.value}
-	var recover = function() {return fn(stream._state.error)}
-	return initDependency(createStream(), [stream], derive, recover)
+	var recover = function() {return absorb(self, fn(stream._state.error))}
+	return initDependency(self, [stream], derive, recover)
 }
 function combine(fn, streams) {
 	return initDependency(createStream(), streams, function() {
@@ -112,6 +115,16 @@ function combine(fn, streams) {
 		return fn.apply(this, streams.concat([streams.filter(changed)]))
 	}, undefined)
 }
+function absorb(stream, value) {
+	if (value != null && value.constructor === createStream) {
+		value.error.map(stream.error)
+		value.map(stream)
+		if (value._state.state === 0) return HALT
+		if (value._state.error) throw value._state.error
+		value = value._state.value
+	}
+	return value
+}
 function initDependency(dep, streams, derive, recover) {
 	var state = dep._state
 	state.derive = derive
@@ -145,6 +158,7 @@ function unregisterStream(stream) {
 function map(fn) {return combine(function(stream) {return fn(stream())}, [this])}
 function ap(stream) {return combine(function(s1, s2) {return s1()(s2())}, [this, stream])}
 function valueOf() {return this._state.value}
+function toJSON() {return JSON.stringify(this._state.value)}
 function active(stream) {return stream._state.state === 1}
 function changed(stream) {return stream._state.changed}
 function notEnded(stream) {return stream._state.state !== 2}
@@ -154,7 +168,7 @@ function reject(e) {
 	stream.error(e)
 	return stream
 }
-var Stream = {stream: createStream, combine: combine, reject: reject}
+var Stream = {stream: createStream, combine: combine, reject: reject, HALT: HALT}
 function Node(tag, key, attrs, children, text, dom) {
 	return {tag: tag, key: key, attrs: attrs, children: children, text: text, dom: dom, domSize: undefined, state: {}, events: undefined, instance: undefined}
 }
@@ -782,7 +796,11 @@ var requestService = function($window) {
 						
 						stream(response)
 					}
-					else stream.error(new Error(xhr.responseText))
+					else {
+						var error = new Error(xhr.responseText)
+						for (var key in response) error[key] = response[key]
+						stream.error(error)
+					}
 				}
 				catch (e) {
 					stream.error(e)
@@ -892,6 +910,7 @@ var parseQueryString = function(string) {
 }
 var coreRouter = function($window) {
 	var supportsPushState = typeof $window.history.pushState === "function" && $window.location.protocol !== "file:"
+	var callAsync = typeof setImmediate === "function" ? setImmediate : setTimeout
 	var prefix = "#!"
 	function setPrefix(value) {prefix = value}
 	function normalize(fragment) {
@@ -939,7 +958,7 @@ var coreRouter = function($window) {
 		if (supportsPushState) {
 			if (options && options.replace) $window.history.replaceState(null, null, prefix + path)
 			else $window.history.pushState(null, null, prefix + path)
-			$window.onpopstate()
+			callAsync($window.onpopstate)
 		}
 		else $window.location.href = prefix + path
 	}
@@ -991,7 +1010,7 @@ var throttle = function(callback) {
 		}
 		else if (pending === null) {
 			pending = timeout(function() {
-				pending = 0
+				pending = null
 				callback()
 				last = new Date().getTime()
 			}, time - (now - last))
diff --git a/router/router.js b/router/router.js
index cd2cdac6..a6054424 100644
--- a/router/router.js
+++ b/router/router.js
@@ -5,6 +5,7 @@ var parseQueryString = require("../querystring/parse")
 
 module.exports = function($window) {
 	var supportsPushState = typeof $window.history.pushState === "function" && $window.location.protocol !== "file:"
+	var callAsync = typeof setImmediate === "function" ? setImmediate : setTimeout
 
 	var prefix = "#!"
 	function setPrefix(value) {prefix = value}
@@ -60,7 +61,7 @@ module.exports = function($window) {
 		if (supportsPushState) {
 			if (options && options.replace) $window.history.replaceState(null, null, prefix + path)
 			else $window.history.pushState(null, null, prefix + path)
-			$window.onpopstate()
+			callAsync($window.onpopstate)
 		}
 		else $window.location.href = prefix + path
 	}
diff --git a/router/tests/index.html b/router/tests/index.html
index 330a2391..cdacf44b 100644
--- a/router/tests/index.html
+++ b/router/tests/index.html
@@ -6,6 +6,7 @@
 	<body>
 		<script src="../../module/module.js"></script>
 		<script src="../../ospec/ospec.js"></script>
+		<script src="../../test-utils/callAsync.js"></script>
 		<script src="../../test-utils/parseURL.js"></script>
 		<script src="../../test-utils/pushStateMock.js"></script>
 
diff --git a/router/tests/test-defineRoutes.js b/router/tests/test-defineRoutes.js
index 01b0f52d..8c4f5055 100644
--- a/router/tests/test-defineRoutes.js
+++ b/router/tests/test-defineRoutes.js
@@ -17,6 +17,13 @@ o.spec("Router.defineRoutes", function() {
 				onFail = o.spy()
 			})
 
+			o("calls onRouteChange on init", function() {
+				$window.location.href = prefix + "/a"
+				router.defineRoutes({"/a": {data: 1}}, onRouteChange, onFail)
+				
+				o(onRouteChange.callCount).equals(1)
+			})
+			
 			o("resolves to route", function() {
 				$window.location.href = prefix + "/test"
 				router.defineRoutes({"/test": {data: 1}}, onRouteChange, onFail)
diff --git a/router/tests/test-setPath.js b/router/tests/test-setPath.js
index 69381c04..a9ef6450 100644
--- a/router/tests/test-setPath.js
+++ b/router/tests/test-setPath.js
@@ -1,6 +1,7 @@
 "use strict"
 
 var o = require("../../ospec/ospec")
+var callAsync = require("../../test-utils/callAsync")
 var pushStateMock = require("../../test-utils/pushStateMock")
 var Router = require("../../router/router")
 
@@ -17,6 +18,28 @@ o.spec("Router.setPath", function() {
 				onFail = o.spy()
 			})
 
+			o("setPath calls onRouteChange asynchronously", function(done) {
+				$window.location.href = prefix + "/a"
+				router.defineRoutes({"/a": {data: 1}, "/b": {data: 2}}, onRouteChange, onFail)
+				router.setPath("/b")
+
+				o(onRouteChange.callCount).equals(1)
+				callAsync(function() {
+					o(onRouteChange.callCount).equals(2)
+					done()
+				})
+			})
+			o("setPath calls onFail asynchronously", function(done) {
+				$window.location.href = prefix + "/a"
+				router.defineRoutes({"/a": {data: 1}, "/b": {data: 2}}, onRouteChange, onFail)
+				router.setPath("/c")
+
+				o(onFail.callCount).equals(0)
+				callAsync(function() {
+					o(onFail.callCount).equals(1)
+					done()
+				})
+			})
 			o("sets route via API", function() {
 				$window.location.href = prefix + "/test"
 				router.defineRoutes({"/test": {data: 1}, "/other/:a/:b...": {data: 2}}, onRouteChange, onFail)
diff --git a/test-utils/tests/index.html b/test-utils/tests/index.html
index bad33bac..4e5a6234 100644
--- a/test-utils/tests/index.html
+++ b/test-utils/tests/index.html
@@ -13,6 +13,7 @@
 		<script src="../../test-utils/pushStateMock.js"></script>
 		<script src="../../test-utils/xhrMock.js"></script>
 		<script src="../../test-utils/domMock.js"></script>
+		<script src="test-callAsync.js"></script>
 		<script src="test-parseURL.js"></script>
 		<script src="test-pushStateMock.js"></script>
 		<script src="test-xhrMock.js"></script>
diff --git a/test-utils/tests/test-callAsync.js b/test-utils/tests/test-callAsync.js
new file mode 100644
index 00000000..37d6defd
--- /dev/null
+++ b/test-utils/tests/test-callAsync.js
@@ -0,0 +1,25 @@
+"use strict"
+
+var o = require("../../ospec/ospec")
+var callAsync = require("../../test-utils/callAsync")
+
+o.spec("callAsync", function() {
+	o("works", function(done) {
+		var count = 0
+		callAsync(function() {
+			o(count).equals(1)
+			done()
+		})
+		count++
+	})
+	o("gets called before setTimeout", function(done) {
+		var timeout
+		callAsync(function() {
+			clearTimeout(timeout)
+			done()
+		})
+		timeout = setTimeout(function() {
+			throw new Error("callAsync was called too slow")
+		}, 0)
+	})
+})
\ No newline at end of file