diff --git a/Gemfile.lock b/Gemfile.lock
index 5675737..de7a29e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -14,7 +14,7 @@ GEM
       citeproc (~> 1.0, >= 1.0.9)
       csl (~> 1.6)
     colorator (1.1.0)
-    concurrent-ruby (1.3.4)
+    concurrent-ruby (1.3.7)
     csl (1.6.0)
       namae (~> 1.0)
       rexml