diff --git a/Gemfile.lock b/Gemfile.lock
index ac8eb43..301093b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -53,7 +53,7 @@ GEM
     minitest (5.5.1)
     multi_json (1.10.1)
     pg (0.18.1)
-    rack (1.5.2)
+    rack (1.5.5)
     rack-test (0.6.3)
       rack (>= 1.0)
     rails (4.1.6)