diff --git a/Library/Homebrew/cask/verify.rb b/Library/Homebrew/cask/verify.rb
index ca0c0ddeea..f31d234c42 100644
--- a/Library/Homebrew/cask/verify.rb
+++ b/Library/Homebrew/cask/verify.rb
@@ -1,6 +1,9 @@
 # frozen_string_literal: true
 
 module Cask
+  # Helper module for verifying a cask's checksum.
+  #
+  # @api private
   module Verify
     module_function