diff --git a/chapter_01/Gemfile.lock b/chapter_01/Gemfile.lock
index 99375d3..ce02a1e 100644
--- a/chapter_01/Gemfile.lock
+++ b/chapter_01/Gemfile.lock
@@ -17,7 +17,7 @@ GEM
     diff-lcs (1.1.3)
     ffi (1.0.11)
     i18n (0.6.0)
-    json (1.7.3)
+    json (2.3.0)
     mime-types (1.19)
     multi_json (1.3.6)
     rack (1.4.1)