diff --git a/chapter_01/Gemfile.lock b/chapter_01/Gemfile.lock
index 99375d3..add8d5e 100644
--- a/chapter_01/Gemfile.lock
+++ b/chapter_01/Gemfile.lock
@@ -20,7 +20,7 @@ GEM
     json (1.7.3)
     mime-types (1.19)
     multi_json (1.3.6)
-    rack (1.4.1)
+    rack (1.6.13)
     rack-protection (1.2.0)
       rack
     rack-test (0.6.1)