diff --git a/Gemfile.lock b/Gemfile.lock
index 9a0d00d..efd0fca 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -52,7 +52,7 @@ GEM
     mime-types (2.4.3)
     minitest (5.4.3)
     multi_json (1.10.1)
-    rack (1.5.2)
+    rack (1.5.5)
     rack-test (0.6.2)
       rack (>= 1.0)
     rails (4.1.8)