diff --git a/Gemfile.lock b/Gemfile.lock
index a20d9d9..490968a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -15,7 +15,7 @@ GEM
     coffee-script-source (1.11.1)
     colorator (1.1.0)
     commonmarker (0.23.7)
-    concurrent-ruby (1.1.10)
+    concurrent-ruby (1.3.7)
     dnsruby (1.61.9)
       simpleidn (~> 0.1)
     em-websocket (0.5.3)