1 files changed, 3 insertions, 0 deletions
diff --git a/tool/id2token.rb b/tool/id2token.rb
index 191b872c5f..706154ecfb 100755
--- a/tool/id2token.rb
+++ b/tool/id2token.rb
@@ -1,5 +1,8 @@
 #! /usr/bin/ruby -p
 # -*- coding: us-ascii -*-
+
+# Used to build the Ruby parsing code in common.mk and Ripper.
+
 BEGIN {
   require 'optparse'
   $:.unshift(File.dirname(__FILE__))