diff --git a/Gemfile.lock b/Gemfile.lock
index 73dad80..183ec39 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -64,7 +64,7 @@ GEM
     net-http-persistent (2.9.4)
     netrc (0.10.3)
     power_assert (0.2.2)
-    rack (1.5.2)
+    rack (1.5.5)
     rack-test (0.6.2)
       rack (>= 1.0)
     rake (10.4.0)