diff --git a/challenges/decrypto/challenge/Gemfile.lock b/challenges/decrypto/challenge/Gemfile.lock
index b87be9b..07ed9f6 100644
--- a/challenges/decrypto/challenge/Gemfile.lock
+++ b/challenges/decrypto/challenge/Gemfile.lock
@@ -15,7 +15,7 @@ GEM
     daemons (1.3.1)
     docile (1.1.5)
     eventmachine (1.2.7)
-    json (2.1.0)
+    json (2.3.1)
     multi_json (1.13.1)
     mustermann (1.0.3)
     optimist (3.0.0)