diff --git a/presentations/join-the-ruby-line/todo/Gemfile.lock b/presentations/join-the-ruby-line/todo/Gemfile.lock
index 4e2ca11..a70274a 100644
--- a/presentations/join-the-ruby-line/todo/Gemfile.lock
+++ b/presentations/join-the-ruby-line/todo/Gemfile.lock
@@ -30,7 +30,7 @@ GEM
     ffi (1.9.6)
     hike (1.2.3)
     hitimes (1.2.2)
-    json (1.8.2)
+    json (2.3.1)
     listen (2.8.5)
       celluloid (>= 0.15.2)
       rb-fsevent (>= 0.9.3)