diff --git a/Gemfile b/Gemfile
index 2495beb..e6257b7 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,7 @@ source "https://rubygems.org"
 
 gem "sinatra", "~> 1.4.7"
 gem "sinatra-contrib", "~> 1.4.7"
-gem "rack", "~> 1.6.4"
+gem "rack", "~> 1.6.12"
 gem "sass", "~> 3.4.22"
 gem "coffee-script", "~> 2.4.1"
 gem "sprockets", "~> 3.6.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index af948cc..1911e42 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -10,7 +10,7 @@ GEM
     concurrent-ruby (1.0.2)
     execjs (2.7.0)
     multi_json (1.12.1)
-    rack (1.6.4)
+    rack (1.6.12)
     rack-protection (1.5.3)
       rack
     rack-test (0.6.3)
@@ -38,7 +38,7 @@ PLATFORMS
 DEPENDENCIES
   chronic (~> 0.10.2)
   coffee-script (~> 2.4.1)
-  rack (~> 1.6.4)
+  rack (~> 1.6.12)
   sass (~> 3.4.22)
   sinatra (~> 1.4.7)
   sinatra-contrib (~> 1.4.7)