diff --git a/Library/Homebrew/vendor/Gemfile.lock b/Library/Homebrew/vendor/Gemfile.lock
index 81686139d9..910bf2da62 100644
--- a/Library/Homebrew/vendor/Gemfile.lock
+++ b/Library/Homebrew/vendor/Gemfile.lock
@@ -8,7 +8,7 @@ GEM
       tzinfo (~> 1.1)
     ast (2.4.0)
     backports (3.11.4)
-    concurrent-ruby (1.1.0)
+    concurrent-ruby (1.0.5)
     i18n (1.1.0)
       concurrent-ruby (~> 1.0)
     jaro_winkler (1.5.1)