diff --git a/Gemfile.lock b/Gemfile.lock
index 5718f65..a1132b7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -44,7 +44,7 @@ GEM
       rack (>= 1.2, < 3)
     power_assert (1.1.5)
     psych (3.1.0)
-    rack (2.0.8)
+    rack (2.2.3)
     rake (13.0.1)
     rdoc (6.2.1)
     semver2 (3.4.2)