diff --git a/caldecott_helper/Gemfile b/caldecott_helper/Gemfile
index ccabb3d..9e760e9 100644
--- a/caldecott_helper/Gemfile
+++ b/caldecott_helper/Gemfile
@@ -1,6 +1,6 @@
 source "http://rubygems.org"
 
-gem 'rack', '~> 1.2.0'
+gem 'rack', '~> 1.6.12'
 gem 'caldecott', '= 0.0.3'
 gem 'bundler'
 gem 'em-websocket'
diff --git a/caldecott_helper/Gemfile.lock b/caldecott_helper/Gemfile.lock
index 4d6c777..91a9d5e 100644
--- a/caldecott_helper/Gemfile.lock
+++ b/caldecott_helper/Gemfile.lock
@@ -23,7 +23,7 @@ GEM
     escape_utils (0.2.4)
     eventmachine (0.12.10)
     json (1.6.1)
-    rack (1.2.4)
+    rack (1.6.12)
     sinatra (1.2.7)
       rack (~> 1.1)
       tilt (>= 1.2.2, < 2.0)
@@ -43,6 +43,6 @@ DEPENDENCIES
   caldecott (= 0.0.3)
   em-websocket
   json
-  rack (~> 1.2.0)
+  rack (~> 1.6.12)
   thin
   uuidtools