diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index 684ffa3bbe..0da32495f1 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -21,6 +21,9 @@ require "cmd/install"
 require "find"
 require "utils/spdx"
 
+# Installer for a formula.
+#
+# @api private
 class FormulaInstaller
   include FormulaCellarChecks
   extend Predicable