diff --git a/Gemfile b/Gemfile
index 9dbe67a4256..e008ae8baae 100644
--- a/Gemfile
+++ b/Gemfile
@@ -80,6 +80,7 @@ gem 'fast_xs'
 gem 'fast_xor', git: 'https://github.com/CodeMonkeySteve/fast_xor.git'
 gem 'fastimage'
 gem 'fog', '1.18.0', require: false
+gem 'unf', require: false
 
 gem 'email_reply_parser', git: 'https://github.com/lawrencepit/email_reply_parser.git'
 
diff --git a/Gemfile_rails4.lock b/Gemfile_rails4.lock
index f671e86997b..e81d78853be 100644
--- a/Gemfile_rails4.lock
+++ b/Gemfile_rails4.lock
@@ -446,6 +446,9 @@ GEM
     uglifier (2.2.1)
       execjs (>= 0.3.0)
       multi_json (~> 1.0, >= 1.0.2)
+    unf (0.1.3)
+      unf_ext
+    unf_ext (0.0.6)
     unicorn (4.6.3)
       kgio (~> 2.6)
       rack
@@ -541,5 +544,6 @@ DEPENDENCIES
   thin
   timecop
   uglifier
+  unf
   unicorn
   vestal_versions!