diff --git a/docs/Gemfile.lock b/docs/Gemfile.lock
index e964fe8..47cd21b 100644
--- a/docs/Gemfile.lock
+++ b/docs/Gemfile.lock
@@ -4,7 +4,7 @@ GEM
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
-    concurrent-ruby (1.1.4)
+    concurrent-ruby (1.3.7)
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)