diff --git a/lib/pathname_builtin.rb b/lib/pathname_builtin.rb
index d9c5d5b..17299d4 100644
--- a/lib/pathname_builtin.rb
+++ b/lib/pathname_builtin.rb
@@ -215,6 +215,9 @@ def initialize(path)
     @path = File.path(path).dup
   end
 
+  #
+  # Freze self.
+  #
   def freeze
     super
     @path.freeze