diff --git a/app/Gemfile.lock b/app/Gemfile.lock
index 18420c8..b5914b3 100644
--- a/app/Gemfile.lock
+++ b/app/Gemfile.lock
@@ -93,7 +93,7 @@ GEM
       rack-test (>= 0.6.3)
       regexp_parser (>= 1.5, < 3.0)
       xpath (~> 3.2)
-    concurrent-ruby (1.2.3)
+    concurrent-ruby (1.3.7)
     connection_pool (2.4.1)
     crass (1.0.6)
     date (3.3.4)