diff --git a/Library/Homebrew/requirements/arch_requirement.rb b/Library/Homebrew/requirements/arch_requirement.rb
index 03a988c76b..dc9d81320f 100644
--- a/Library/Homebrew/requirements/arch_requirement.rb
+++ b/Library/Homebrew/requirements/arch_requirement.rb
@@ -2,6 +2,9 @@
 
 require "requirement"
 
+# A requirement on a specific architecture.
+#
+# @api private
 class ArchRequirement < Requirement
   fatal true