diff --git a/Gemfile.lock b/Gemfile.lock
index 54ba4f3..77ca585 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -4,7 +4,7 @@ GEM
     addressable (2.8.1)
       public_suffix (>= 2.0.2, < 6.0)
     colorator (1.1.0)
-    concurrent-ruby (1.1.10)
+    concurrent-ruby (1.3.7)
     cssminify2 (2.0.1)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)