diff --git a/Library/Homebrew/dev-cmd/update-maintainers.rb b/Library/Homebrew/dev-cmd/update-maintainers.rb
index 2b76426e55c36..98923595e3e12 100644
--- a/Library/Homebrew/dev-cmd/update-maintainers.rb
+++ b/Library/Homebrew/dev-cmd/update-maintainers.rb
@@ -5,6 +5,8 @@
 require "utils/github"
 require "manpages"
 
+require "active_support/core_ext/hash/slice"
+
 module Homebrew
   extend T::Sig