diff --git a/app/assets/javascripts/discourse/dialects/mention_dialect.js b/app/assets/javascripts/discourse/dialects/mention_dialect.js
index 55687257bc..0e13d02637 100644
--- a/app/assets/javascripts/discourse/dialects/mention_dialect.js
+++ b/app/assets/javascripts/discourse/dialects/mention_dialect.js
@@ -10,9 +10,9 @@ Discourse.Dialect.inlineRegexp({
 
   emitter: function(matches) {
     var username = matches[1],
-        mentionLookup = this.dialect.options.mentionLookup || Discourse.Mention.lookupCache;
+        mentionLookup = this.dialect.options.mentionLookup;
 
-    if (mentionLookup(username.substr(1))) {
+    if (mentionLookup && mentionLookup(username.substr(1))) {
       return ['a', {'class': 'mention', href: Discourse.getURL("/users/") + username.substr(1).toLowerCase()}, username];
     } else {
       return ['span', {'class': 'mention'}, username];
diff --git a/app/assets/javascripts/discourse/lib/mention.js b/app/assets/javascripts/discourse/lib/mention.js
index bc8b6edc83..7668d7bbc9 100644
--- a/app/assets/javascripts/discourse/lib/mention.js
+++ b/app/assets/javascripts/discourse/lib/mention.js
@@ -1,53 +1,59 @@
+
+// A local cache lookup
+var localCache = [];
+
+
 /**
-  Helps us determine whether someone has been mentioned by looking up their username.
+  Lookup a username and return whether it is exists or not.
+
+  @function lookup
+  @param {String} username to look up
+  @return {Promise} promise that results to whether the name was found or not
+**/
+function lookup(username) {
+  return new Em.RSVP.Promise(function (resolve) {
+    var cached = localCache[username];
+
+    // If we have a cached answer, return it
+    if (typeof cached !== "undefined") {
+      resolve(cached);
+    } else {
+      Discourse.ajax("/users/is_local_username", { data: { username: username } }).then(function(r) {
+        localCache[username] = r.valid;
+        resolve(r.valid);
+      });
+    }
+  });
+}
+
+/**
+  Help us link directly to a mentioned user's profile if the username exists.
 
   @class Mention
   @namespace Discourse
   @module Discourse
 **/
-Discourse.Mention = (function() {
-  var localCache = {};
+Discourse.Mention = {
 
-  var cache = function(name, valid) {
-    localCache[name] = valid;
-  };
+  /**
+    Paints an element in the DOM with the appropriate classes and markup if the username
+    it is mentioning exists.
 
-  var lookupCache = function(name) {
-    return localCache[name];
-  };
-
-  var lookup = function(name, callback) {
-    var cached = lookupCache(name);
-    if (cached === true || cached === false) {
-      callback(cached);
-      return false;
-    } else {
-      Discourse.ajax("/users/is_local_username", { data: { username: name } }).then(function(r) {
-        cache(name, r.valid);
-        callback(r.valid);
-      });
-      return true;
-    }
-  };
-
-  var load = function(e) {
+    @method paint
+    @param {Element} the element in the DOM to decorate
+  **/
+  paint: function(e) {
     var $elem = $(e);
     if ($elem.data('mention-tested')) return;
-    var username = $elem.text();
-    username = username.substr(1);
-    var loading = lookup(username, function(valid) {
-      if (valid) {
-        return $elem.replaceWith("<a href='" + Discourse.getURL("/users/") + (username.toLowerCase()) + "' class='mention'>@" + username + "</a>");
+    var username = $elem.text().substr(1);
+
+    $elem.addClass('mention-loading');
+    lookup(username).then(function(found) {
+      if (found) {
+        $elem.replaceWith("<a href='" + Discourse.getURL("/users/") + username.toLowerCase() + "' class='mention'>@" + username + "</a>");
       } else {
-        return $elem.removeClass('mention-loading').addClass('mention-tested');
+        $elem.removeClass('mention-loading').addClass('mention-tested');
       }
     });
-    if (loading) {
-      return $elem.addClass('mention-loading');
-    }
-  };
-
-  return { load: load, lookup: lookup, lookupCache: lookupCache };
-})();
-
-
+  }
+};
diff --git a/app/assets/javascripts/discourse/views/composer/composer_view.js b/app/assets/javascripts/discourse/views/composer/composer_view.js
index ad3080ff63..90e9ef8c9e 100644
--- a/app/assets/javascripts/discourse/views/composer/composer_view.js
+++ b/app/assets/javascripts/discourse/views/composer/composer_view.js
@@ -157,7 +157,7 @@ Discourse.ComposerView = Discourse.View.extend(Ember.Evented, {
       Discourse.Onebox.load(e, refresh);
     });
     $('span.mention', $wmdPreview).each(function(i, e) {
-      Discourse.Mention.load(e, refresh);
+      Discourse.Mention.paint(e);
     });
 
     this.trigger('previewRefreshed', $wmdPreview);
diff --git a/test/javascripts/lib/markdown_test.js b/test/javascripts/lib/markdown_test.js
index ec18c80a2d..e46ebc946e 100644
--- a/test/javascripts/lib/markdown_test.js
+++ b/test/javascripts/lib/markdown_test.js
@@ -5,7 +5,7 @@ module("Discourse.Markdown", {
 });
 
 var cooked = function(input, expected, text) {
-  var result = Discourse.Markdown.cook(input, {mentionLookup: false, sanitize: true});
+  var result = Discourse.Markdown.cook(input, {sanitize: true});
   equal(result, expected, text);
 };
 
@@ -243,7 +243,7 @@ test("Heading", function() {
 test("Oneboxing", function() {
 
   var matches = function(input, regexp) {
-    return Discourse.Markdown.cook(input, {mentionLookup: false }).match(regexp);
+    return Discourse.Markdown.cook(input).match(regexp);
   };
 
   ok(!matches("- http://www.textfiles.com/bbs/MINDVOX/FORUMS/ethics\n\n- http://drupal.org", /onebox/),
diff --git a/test/javascripts/mdtest/mdtest.js.erb b/test/javascripts/mdtest/mdtest.js.erb
index b5d7c8632e..5bf4c22fe0 100644
--- a/test/javascripts/mdtest/mdtest.js.erb
+++ b/test/javascripts/mdtest/mdtest.js.erb
@@ -14,7 +14,7 @@ function normalize(str) {
 }
 
 var md = function(input, expected, text) {
-  var result = Discourse.Markdown.cook(input, {mentionLookup: false, sanitize: true, traditional_markdown_linebreaks: true}),
+  var result = Discourse.Markdown.cook(input, {sanitize: true, traditional_markdown_linebreaks: true}),
       resultNorm = normalize(result),
       expectedNorm = normalize(expected),
       same = (result === expected) || (resultNorm === expectedNorm);