diff --git a/Gemfile.lock b/Gemfile.lock
index c9c0cda..69cb77c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -32,7 +32,7 @@ GEM
     benchmark (0.4.0)
     bigdecimal (3.1.8)
     builder (3.2.4)
-    concurrent-ruby (1.2.2)
+    concurrent-ruby (1.3.8)
     connection_pool (2.4.1)
     crass (1.0.6)
     diff-lcs (1.5.0)