diff --git a/app/models/Invite.js b/app/models/Invite.js
index dd5bcec..2159cb5 100644
--- a/app/models/Invite.js
+++ b/app/models/Invite.js
@@ -14,8 +14,8 @@ var InviteSchema = mongoose.Schema({
     exp: Date
 });
 
-InviteSchema.methods.use = function(canonicalname, cb) {
+/*InviteSchema.methods.use = function(canonicalname, cb) {
     return this.model('Invite').updateOne({code: this.code}, {recipient: canonicalname, used: Date.now()}, cb);
-};
+};*/
 
 module.exports = mongoose.model('Invite', InviteSchema);
\ No newline at end of file
diff --git a/app/routes/auth.js b/app/routes/auth.js
index 381d972..d14ce2a 100644
--- a/app/routes/auth.js
+++ b/app/routes/auth.js
@@ -1,118 +1,129 @@
-var express = require('express');
-var router = express.Router();
+'use strict';
 
-var User = require('../models/User.js');
-var Invite = require('../models/Invite.js');
+const express = require('express');
+const router = express.Router();
 
-var passport = require('passport');
+const User = require('../models/User.js');
+const Invite = require('../models/Invite.js');
 
-var async = require('async');
+const passport = require('passport');
 
-// Normalizes, decomposes, and lowercases a unicode string
-function canonicalize(username) {
-    return username.normalize('NFKD').toLowerCase();
+const async = require('async');
+
+function memoize(fn) {
+    let cache = {};
+
+    return async function() {
+        let args = JSON.stringify(arguments);
+        cache[args] = cache[args] || fn.apply(this, arguments);
+        return cache[args];
+    };
 }
 
-// Checks if an invite code is valid
-// Returns the invite object if valid
-function checkInvite(code, cb) {
-    Invite.findOne({code: code}, function (err, invite) {
-        if (err)
-            cb(err);
-        else if (!invite)
-            cb('Invalid invite code.');
-        else if (invite.used)
-            cb('Invite already used.');
-        else if (invite.exp < Date.now())
-            cb('Invite expired.');
-        else
-            cb(null, invite);
-    });
+const asyncMiddleware = fn =>
+    (req, res, next) => {
+        Promise.resolve(fn(req, res, next))
+            .catch(next);
+    };
+
+// Normalizes, decomposes, and lowercases a utf-8 string
+const canonicalizeUsername = username => username.normalize('NFKD').toLowerCase();
+
+// Check if a canonical name is valid
+async function validateUsername(username, canonicalName, sanitize) {
+    if (canonicalName.length > 36)
+        return {valid: false, message: 'Username too long.'};
+
+    if (canonicalName !== sanitize(canonicalName).replace(/\s/g, ''))
+        return {valid: false, message: 'Username contains invalid characters.'};
+
+    const count = await User.countDocuments({canonicalname: canonicalName});
+
+    if (count !== 0)
+        return {valid: false, message: 'Username in use.'};
+
+    return {valid: true};
 }
 
-// Validates the username, then registers the user in the database using the given invite.
-function registerUser(username, password, invite, sanitize, cb) {
-    async.series([
-        function (cb) {
-            // Canonicalize and sanitize the username, checking for HTML
-            var canonicalName = canonicalize(username);
-            var sanitizedName = sanitize(canonicalName).replace(/\s/g,'');
+// Query the database for a valid invite code. An error message property is set if invalid.
+async function validateInvite(code) {
+    const invite = await Invite.findOne({code: code});
 
-            if (sanitizedName !== canonicalName)
-                cb('Username contains invalid characters.');
-            else if (canonicalName.length > 36)
-                cb('Username too long.');
-            else
-                cb(null);
-        },
-        function(cb) {
-            async.waterfall([
-                function(cb) {
-                    User.count({canonicalname: canonicalize(username)}, cb);
-                },
-                function(count, cb) {
-                    if (count !== 0)
-                        cb('Username in use.');
-                    else
-                        cb(null);
-                }
-            ], cb);
-        },
-        function (cb) {
-            User.register(new User({
-                username: username,
-                canonicalname: canonicalize(username),
-                scope: invite.scope,
-                date: Date.now()
-            }), password, cb);
-        },
-        function (cb) {
-            invite.use(canonicalize(username), cb);
-        }
-    ], function (err) {
-        cb(err);
-    });
+    if (!invite)
+        return {valid: false, message: 'Invalid invite code.'};
+
+    if (invite.used)
+        return {valid: false, message: 'Invite already used.'};
+
+    if (invite.exp < Date.now())
+        return {valid: false, message: 'Invite expired.'};
+
+    return {valid: true, invite: invite};
 }
 
 // Authenticates and creates the required session variables
 function setupSession(username, req, res, cb) {
     // Body needs to contain canonical name for proper authentication
-    req.body.canonicalname = canonicalize(req.body.username);
+    req.body.canonicalname = canonicalizeUsername(req.body.username);
 
     passport.authenticate('local')(req, res, function () {
         req.session.save(function (err) {
             if (!err) {
                 req.session.passport.username = username;
-                req.session.passport.canonicalname = canonicalize(username);
+                req.session.passport.canonicalname = canonicalizeUsername(username);
             }
             cb(err);
         });
     });
 }
 
-router.post('/register', function (req, res) {
-    async.waterfall([
-        function (cb) {
-            checkInvite(req.body.invite, cb);
-        },
-        function (invite, cb) {
-            registerUser(req.body.username, req.body.password, invite, req.sanitize, cb);
-        },
-        function (cb) {
-            setupSession(req.body.username, req, res, cb);
-        }
-    ], function (err) {
-        if (err) {
-            res.status(401).json({'message': err});
-        } else {
-            res.status(200).json({'message': 'Registration successful.'});
-        }
+router.post('/register', asyncMiddleware(async (req, res, next) => {
+    const reqUsername = req.body.username;
+    const reqPassword = req.body.password;
+    const reqInviteCode = req.body.invite;
+    const canonicalName = canonicalizeUsername(reqUsername);
+
+    // memoized verification functions
+    const checkInvite = memoize(async () => validateInvite(reqInviteCode));
+    const checkUsername = memoize(async () => validateUsername(reqUsername, canonicalName, req.sanitize));
+
+    // Validate the invite and username
+    const [inviteStatus, usernameStatus] = await Promise.all([checkInvite(), checkUsername()]);
+
+    // Make sure invite was valid
+    if (!inviteStatus.valid)
+        return res.status(422).json({'message': inviteStatus.message});
+
+    // Make sure the username was valid
+    if (!usernameStatus.valid)
+        return res.status(422).json({'message': usernameStatus.message});
+
+    // Create the new user object
+    const user = new User({
+        username: reqUsername,
+        canonicalname: canonicalName,
+        scope: inviteStatus.invite.scope,
+        date: Date.now()
     });
-});
+
+    // memoized password setting, user saving, and invite updating functions
+    const updateInvite = memoize(async () =>
+        Invite.updateOne({code: inviteStatus.invite.code}, {recipient: canonicalName, used: Date.now()}));
+    const setPassword = memoize(async () => user.setPassword(reqPassword));
+    const saveUser = memoize(async () => {
+        await setPassword();
+        return user.save();
+    });
+
+    // Set the password, save the user, and update the invite code
+    await Promise.all([updateInvite(), setPassword(), saveUser()]);
+
+    res.status(200).json({'message': 'Registration successful.'});
+}));
 
 router.post('/login', function (req, res, next) {
     // Take 'username' from the form and canonicalize it for authentication.
-    req.body.canonicalname = canonicalize(req.body.username);
+    req.body.canonicalname = canonicalizeUsername(req.body.username);
 
     async.waterfall([
         function (cb) {
@@ -128,7 +139,7 @@ router.post('/login', function (req, res, next) {
         },
         function (cb) {
             req.session.passport.username = req.body.username;
-            req.session.passport.canonicalname = canonicalize(req.body.username);
+            req.session.passport.canonicalname = canonicalizeUsername(req.body.username);
             cb();
         }
     ], function (err) {