diff --git a/Gemfile b/Gemfile
index 947b17c8..9e69ed44 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 
-# Use rails as framework 
+# Use rails as framework
 gem 'rails', '~> 4.1'
 
 # Use mysql as the database for Active Record
@@ -27,6 +27,7 @@ gem 'cancan'
 gem 'transitions', :require => %w( transitions active_record/transitions )
 
 # Use acts_as_commentable_with_threading for comments
+gem 'awesome_nested_set', '~> 3.0.0.rc.5'
 gem 'acts_as_commentable_with_threading'
 
 # Use haml as templating language
@@ -87,13 +88,13 @@ group :development, :test do
   gem 'shoulda'
 end
 
-# FIXME: We should use http://weblog.rubyonrails.org/2012/3/21/strong-parameters/ 
+# FIXME: We should use http://weblog.rubyonrails.org/2012/3/21/strong-parameters/
 gem 'protected_attributes'
 
 # We use this bootstrap/html5 rdoc generator
 gem 'rdoc-generator-fivefish'
 
-# We use factory_girl for seeds 
+# We use factory_girl for seeds
 gem 'factory_girl_rails'
 
 # Use guard and spring for testing in development
diff --git a/Gemfile.lock b/Gemfile.lock
index 5b210e94..db70ef34 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -36,8 +36,8 @@ GEM
     addressable (2.3.6)
     arel (5.0.1.20140414130214)
     ast (2.0.0)
-    awesome_nested_set (2.1.6)
-      activerecord (>= 3.0.0)
+    awesome_nested_set (3.0.0.rc.5)
+      activerecord (>= 4.0.0, < 5)
     axlsx (2.0.1)
       htmlentities (~> 4.3.1)
       nokogiri (>= 1.4.1)
@@ -164,7 +164,7 @@ GEM
     method_source (0.8.2)
     mime-types (1.25.1)
     mini_portile (0.6.0)
-    minitest (5.3.3)
+    minitest (5.3.4)
     multi_json (1.9.2)
     multi_xml (0.5.5)
     multipart-post (2.0.0)
@@ -327,7 +327,7 @@ GEM
     term-ansicolor (1.3.0)
       tins (~> 1.0)
     thor (0.19.1)
-    thread_safe (0.3.3)
+    thread_safe (0.3.4)
     tilt (1.4.1)
     timers (1.1.0)
     tins (1.1.0)
@@ -338,7 +338,7 @@ GEM
     ttfunk (1.1.1)
     turbolinks (2.2.2)
       coffee-rails
-    tzinfo (1.1.0)
+    tzinfo (1.2.1)
       thread_safe (~> 0.1)
     uglifier (2.5.0)
       execjs (>= 0.3.0)
@@ -355,6 +355,7 @@ PLATFORMS
 DEPENDENCIES
   active_model_serializers
   acts_as_commentable_with_threading
+  awesome_nested_set (~> 3.0.0.rc.5)
   axlsx_rails
   bootstrap-sass
   cancan