diff --git a/Gemfile.lock b/Gemfile.lock
index cabca4df..1c9d2209 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -26,7 +26,7 @@ GEM
       execjs
     coffee-script-source (1.12.2)
     colorator (1.1.0)
-    concurrent-ruby (1.2.2)
+    concurrent-ruby (1.3.7)
     csl (1.6.0)
       namae (~> 1.0)
       rexml