diff --git a/appengine/rails-cloudsql-mysql/Gemfile.lock b/appengine/rails-cloudsql-mysql/Gemfile.lock
index 1d68e8fe8..6aab71f55 100644
--- a/appengine/rails-cloudsql-mysql/Gemfile.lock
+++ b/appengine/rails-cloudsql-mysql/Gemfile.lock
@@ -99,7 +99,7 @@ GEM
       rack-test (>= 0.6.3)
       regexp_parser (>= 1.5, < 3.0)
       xpath (~> 3.2)
-    concurrent-ruby (1.3.5)
+    concurrent-ruby (1.3.7)
     connection_pool (2.5.3)
     crass (1.0.6)
     cuprite (0.14.3)