diff --git a/Gemfile.lock b/Gemfile.lock
index 6dba4f8..e369298 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -114,7 +114,7 @@ GEM
       rack-test (>= 0.6.3)
       regexp_parser (>= 1.5, < 3.0)
       xpath (~> 3.2)
-    concurrent-ruby (1.3.1)
+    concurrent-ruby (1.3.7)
     connection_pool (2.4.1)
     crass (1.0.6)
     date (3.3.4)