diff --git a/Library/Homebrew/cask/pkg.rb b/Library/Homebrew/cask/pkg.rb
index 42986319d9..f6c4a2444f 100644
--- a/Library/Homebrew/cask/pkg.rb
+++ b/Library/Homebrew/cask/pkg.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "cask/macos"
+
 module Cask
   class Pkg
     def self.all_matching(regexp, command)