diff --git a/2015/ruby/Gemfile.lock b/2015/ruby/Gemfile.lock
index a145e03..66ad492 100644
--- a/2015/ruby/Gemfile.lock
+++ b/2015/ruby/Gemfile.lock
@@ -1,17 +1,17 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.2.5)
-      i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
-      minitest (~> 5.1)
-      thread_safe (~> 0.3, >= 0.3.4)
-      tzinfo (~> 1.1)
+    activesupport (7.0.3)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (>= 1.6, < 2)
+      minitest (>= 5.1)
+      tzinfo (~> 2.0)
     awesome_print (1.6.1)
     coderay (1.1.0)
     colorize (0.7.7)
-    i18n (0.7.0)
-    json (1.8.3)
+    concurrent-ruby (1.1.10)
+    i18n (1.10.0)
+      concurrent-ruby (~> 1.0)
     letters (0.4.1)
       activesupport
       awesome_print
@@ -24,9 +24,8 @@ GEM
       method_source (~> 0.8.1)
       slop (~> 3.4)
     slop (3.6.0)
-    thread_safe (0.3.5)
-    tzinfo (1.2.2)
-      thread_safe (~> 0.1)
+    tzinfo (2.0.4)
+      concurrent-ruby (~> 1.0)
     xml-simple (1.1.5)
 
 PLATFORMS