diff --git a/Library/Homebrew/checksum.rb b/Library/Homebrew/checksum.rb
index fe0960df4a..84c6c62342 100644
--- a/Library/Homebrew/checksum.rb
+++ b/Library/Homebrew/checksum.rb
@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 
+# A formula's checksum.
+#
+# @api private
 class Checksum
   extend Forwardable