diff --git a/challenges/futurella/challenge/Gemfile.lock b/challenges/futurella/challenge/Gemfile.lock
index 052e274..206531b 100644
--- a/challenges/futurella/challenge/Gemfile.lock
+++ b/challenges/futurella/challenge/Gemfile.lock
@@ -13,7 +13,7 @@ GEM
     daemons (1.3.1)
     docile (1.1.5)
     eventmachine (1.2.7)
-    json (2.1.0)
+    json (2.3.1)
     mustermann (1.0.3)
     optimist (3.0.0)
     power_assert (1.1.3)