diff --git a/ruby/unicorn/Gemfile.lock b/ruby/unicorn/Gemfile.lock
index f475a53..3f9d87a 100644
--- a/ruby/unicorn/Gemfile.lock
+++ b/ruby/unicorn/Gemfile.lock
@@ -2,7 +2,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     kgio (2.10.0)
-    rack (1.6.4)
+    rack (2.1.4)
     raindrops (0.16.0)
     unicorn (5.1.0)
       kgio (~> 2.6)