diff --git a/chrome/content/zotero/xpcom/cookieSandbox.js b/chrome/content/zotero/xpcom/cookieSandbox.js
index 87f34b6a3c..79f34daddf 100755
--- a/chrome/content/zotero/xpcom/cookieSandbox.js
+++ b/chrome/content/zotero/xpcom/cookieSandbox.js
@@ -221,7 +221,7 @@ Zotero.CookieSandbox.prototype = {
 	 */
 	"getCookiesForURI": function(uri) {
 		var hostParts = Zotero.CookieSandbox.normalizeHost(uri.host).split('.'),
-			pathParts = Zotero.CookieSandbox.normalizePath(uri.filePath || uri.path).split('/'),
+			pathParts = Zotero.CookieSandbox.normalizePath(uri.filePath || uri.pathQueryRef).split('/'),
 			cookies = {}, found = false, secure = uri.scheme.toUpperCase() == 'HTTPS';
 		
 		// Fetch cookies starting from the highest level domain
diff --git a/chrome/content/zotero/xpcom/file.js b/chrome/content/zotero/xpcom/file.js
index 2a42ab8696..6583f6275d 100644
--- a/chrome/content/zotero/xpcom/file.js
+++ b/chrome/content/zotero/xpcom/file.js
@@ -449,7 +449,7 @@ Zotero.File = new function(){
 	
 	this.download = Zotero.Promise.coroutine(function* (uri, path) {
 		Zotero.debug("Saving " + (uri.spec ? uri.spec : uri)
-			+ " to " + (path.path ? path.path : path));			
+			+ " to " + (path.pathQueryRef ? path.pathQueryRef : path));
 		
 		var deferred = Zotero.Promise.defer();
 		NetUtil.asyncFetch(uri, function (is, status, request) {
diff --git a/chrome/content/zotero/xpcom/http.js b/chrome/content/zotero/xpcom/http.js
index 3404621264..94b513673f 100644
--- a/chrome/content/zotero/xpcom/http.js
+++ b/chrome/content/zotero/xpcom/http.js
@@ -134,8 +134,7 @@ Zotero.HTTP = new function() {
 			if (options.username) {
 				options.username = options.username.replace(/%2E/, '.');
 				options.password = url.password || null;
-				url = url.clone();
-				url.userPass = '';
+				url = url.mutate().setUserPass('').finalize();
 			}
 			
 			url = url.spec;
diff --git a/chrome/content/zotero/xpcom/proxy.js b/chrome/content/zotero/xpcom/proxy.js
index 3eedd2e70b..85f20ef92f 100644
--- a/chrome/content/zotero/xpcom/proxy.js
+++ b/chrome/content/zotero/xpcom/proxy.js
@@ -509,11 +509,11 @@ Zotero.Proxy.prototype.toProxy = function(uri) {
 		if(param == "%h") {
 			value = this.dotsToHyphens ? uri.hostPort.replace(/-/g, '.') : uri.hostPort;
 		} else if(param == "%p") {
-			value = uri.path.substr(1);
+			value = uri.pathQueryRef.substr(1);
 		} else if(param == "%d") {
-			value = uri.path.substr(0, uri.path.lastIndexOf("/"));
+			value = uri.pathQueryRef.substr(0, uri.pathQueryRef.lastIndexOf("/"));
 		} else if(param == "%f") {
-			value = uri.path.substr(uri.path.lastIndexOf("/")+1)
+			value = uri.pathQueryRef.substr(uri.pathQueryRef.lastIndexOf("/")+1)
 		}
 		
 		proxyURL = proxyURL.substr(0, this.indices[param])+value+proxyURL.substr(this.indices[param]+2);
diff --git a/chrome/content/zotero/xpcom/quickCopy.js b/chrome/content/zotero/xpcom/quickCopy.js
index a279d96d08..258c94bab8 100644
--- a/chrome/content/zotero/xpcom/quickCopy.js
+++ b/chrome/content/zotero/xpcom/quickCopy.js
@@ -172,7 +172,7 @@ Zotero.QuickCopy = new function() {
 			// Accessing some properties may throw for URIs that do not support those
 			// parts. E.g. hostPort throws NS_ERROR_FAILURE for about:blank
 			var urlHostPort = nsIURI.hostPort;
-			var urlPath = nsIURI.path;
+			var urlPath = nsIURI.pathQueryRef;
 		}
 		catch (e) {}
 		
diff --git a/chrome/content/zotero/xpcom/storage/streamListener.js b/chrome/content/zotero/xpcom/storage/streamListener.js
index 7e07903824..ce955705a9 100644
--- a/chrome/content/zotero/xpcom/storage/streamListener.js
+++ b/chrome/content/zotero/xpcom/storage/streamListener.js
@@ -271,6 +271,6 @@ Zotero.Sync.Storage.StreamListener.prototype = {
 	
 	_safeSpec: function (uri) {
 		return uri.scheme + '://' + uri.username + ':********@'
-			+ uri.hostPort + uri.path
+			+ uri.hostPort + uri.pathQueryRef
 	},
 };
diff --git a/chrome/content/zotero/xpcom/storage/webdav.js b/chrome/content/zotero/xpcom/storage/webdav.js
index 55277b2736..ffbd6d1f97 100644
--- a/chrome/content/zotero/xpcom/storage/webdav.js
+++ b/chrome/content/zotero/xpcom/storage/webdav.js
@@ -185,32 +185,23 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 			throw new this.VerificationError("NO_URL");
 		}
 		
-		url = scheme + '://' + url;
-		var dir = "zotero";
 		var username = this.username;
 		var password = this.password;
-		
 		if (!username) {
 			throw new this.VerificationError("NO_USERNAME");
 		}
-		
 		if (!password) {
 			throw new this.VerificationError("NO_PASSWORD");
 		}
 		
-		var ios = Components.classes["@mozilla.org/network/io-service;1"].
-					getService(Components.interfaces.nsIIOService);
-		var uri = ios.newURI(url, null, null);
-		uri.username = encodeURIComponent(username);
-		uri.password = encodeURIComponent(password);
-		if (!uri.spec.match(/\/$/)) {
-			uri.spec += "/";
-		}
-		this._parentURI = uri;
+		url = scheme + '://'
+			+ encodeURIComponent(username) + ':' + encodeURIComponent(password) + '@'
+			+ url
+			+ (url.endsWith('/') ? '' : '/');
 		
-		var uri = uri.clone();
-		uri.spec += "zotero/";
-		this._rootURI = uri;
+		var io = Services.io;
+		this._parentURI = io.newURI(url, null, null);
+		this._rootURI = io.newURI(url + "zotero/", null, null);
 	},
 	
 	
@@ -639,8 +630,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 		
 		if (req.status == 207) {
 			// Test if missing files return 404s
-			let missingFileURI = uri.clone();
-			missingFileURI.spec += "nonexistent.prop";
+			let missingFileURI = uri.mutate().setSpec(uri.spec + "nonexistent.prop").finalize();
 			try {
 				req = yield Zotero.HTTP.request(
 					"GET",
@@ -663,8 +653,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 			}
 			
 			// Test if Zotero directory is writable
-			let testFileURI = uri.clone();
-			testFileURI.spec += "zotero-test-file.prop";
+			let testFileURI = uri.mutate().setSpec(uri.spec + "zotero-test-file.prop").finalize();
 			req = yield Zotero.HTTP.request("PUT", testFileURI, {
 				body: " ",
 				successCodes: [200, 201, 204],
@@ -744,7 +733,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 				createInstance(Components.interfaces.nsIPromptService);
 		var uri = err.uri;
 		if (uri) {
-			var spec = uri.scheme + '://' + uri.hostPort + uri.path;
+			var spec = uri.scheme + '://' + uri.hostPort + uri.pathQueryRef;
 		}
 		
 		var errorTitle, errorMsg;
@@ -763,7 +752,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 			
 			case 403:
 				errorTitle = Zotero.getString('general.permissionDenied');
-				errorMsg = Zotero.getString('sync.storage.error.webdav.permissionDenied', err.channel.URI.path)
+				errorMsg = Zotero.getString('sync.storage.error.webdav.permissionDenied', err.channel.URI.pathQueryRef)
 					+ "\n\n" + Zotero.getString('sync.storage.error.checkFileSyncSettings');
 				break;
 			
@@ -830,7 +819,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 							if (e.status == 403) {
 								errorTitle = Zotero.getString('general.permissionDenied');
 								let rootURI = this.rootURI;
-								let rootSpec = rootURI.scheme + '://' + rootURI.hostPort + rootURI.path
+								let rootSpec = rootURI.scheme + '://' + rootURI.hostPort + rootURI.pathQueryRef
 								errorMsg = Zotero.getString('sync.storage.error.permissionDeniedAtAddress')
 									+ "\n\n" + rootSpec + "\n\n"
 									+ Zotero.getString('sync.storage.error.checkFileSyncSettings');
@@ -965,7 +954,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 		Zotero.debug("Purging orphaned storage files");
 		
 		var uri = this.rootURI;
-		var path = uri.path;
+		var path = uri.pathQueryRef;
 		
 		var contentTypeXML = { "Content-Type": "text/xml; charset=utf-8" };
 		var xmlstr = "<propfind xmlns='DAV:'><prop>"
@@ -1014,7 +1003,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 			if (href.match(/^https?:\/\//)) {
 				let ios = Components.classes["@mozilla.org/network/io-service;1"]
 					.getService(Components.interfaces.nsIIOService);
-				href = ios.newURI(href, null, null).path;
+				href = ios.newURI(href, null, null).pathQueryRef;
 			}
 			
 			let decodedHref = decodeURIComponent(href).normalize();
@@ -1307,9 +1296,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 	 * @return	{nsIURI}					URI of file on storage server
 	 */
 	_getItemURI: function (item) {
-		var uri = this.rootURI;
-		uri.spec = uri.spec + item.key + '.zip';
-		return uri;
+		return this.rootURI.mutate().setSpec(this.rootURI.spec + item.key + '.zip').finalize();
 	},
 	
 	
@@ -1321,9 +1308,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 	 * @return	{nsIURI}					URI of property file on storage server
 	 */
 	_getItemPropertyURI: function (item) {
-		var uri = this.rootURI;
-		uri.spec = uri.spec + item.key + '.prop';
-		return uri;
+		return this.rootURI.mutate().setSpec(this.rootURI.spec + item.key + '.prop').finalize();
 	},
 	
 	
@@ -1337,11 +1322,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 		if (!uri.spec.match(/\.zip$/)) {
 			return false;
 		}
-		var propURI = uri.clone();
-		propURI.QueryInterface(Components.interfaces.nsIURL);
-		propURI.fileName = uri.fileName.replace(/\.zip$/, '.prop');
-		propURI.QueryInterface(Components.interfaces.nsIURI);
-		return propURI;
+		return uri.mutate().setFilePath(uri.filePath.replace(/\.zip$/, '.prop')).finalize();
 	},
 	
 	
@@ -1379,10 +1360,7 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 		for (let i = 0 ; i < files.length; i++) {
 			let fileName = files[i];
 			funcs.push(Zotero.Promise.coroutine(function* () {
-				var deleteURI = this.rootURI.clone();
-				deleteURI.QueryInterface(Components.interfaces.nsIURL);
-				deleteURI.fileName = fileName;
-				deleteURI.QueryInterface(Components.interfaces.nsIURI);
+				var deleteURI = this.rootURI.mutate().setSpec(this.rootURI.spec + fileName).finalize();
 				try {
 					var req = yield Zotero.HTTP.request(
 						"DELETE",
@@ -1411,6 +1389,8 @@ Zotero.Sync.Storage.Mode.WebDAV.prototype = {
 				
 				// If an item file URI, get the property URI
 				var deletePropURI = this._getPropertyURIFromItemURI(deleteURI);
+				// Only nsIURL has fileName
+				deletePropURI.QueryInterface(Ci.nsIURL);
 				
 				// If we already deleted the prop file, skip it
 				if (!deletePropURI || results.deleted.has(deletePropURI.fileName)) {