diff --git a/ChangeLog b/ChangeLog
index da48282c2d..e66a9d7c5c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri May 22 18:44:34 2009  Yuki Sonoda (Yugui)  <yugui@yugui.jp>
+
+	* instruby.rb (rdoc): considers --program-prefix and --program-suffix
+	  for the path to ri documents.
+	  fixes [ruby-core:23519]. c.f. [ruby-dev:38255].
+
 Wed May 20 20:54:37 2009  Yuki Sonoda (Yugui)  <yugui@yugui.jp>
 
 	* spec/.gitignore: ignores rubyspec/ and mspec/.
diff --git a/instruby.rb b/instruby.rb
index c496d89b04..17dc6a4c95 100755
--- a/instruby.rb
+++ b/instruby.rb
@@ -283,7 +283,7 @@ install?(:rdoc) do
   if $rdocdir
     puts "installing rdoc"
 
-    ridatadir = File.join(CONFIG['datadir'], "ri", CONFIG['ruby_version'], "system")
+    ridatadir = File.join(CONFIG['datadir'], CONFIG['ruby_install_name'].sub('ruby', 'ri'), CONFIG['ruby_version'], "system")
     makedirs [ridatadir]
     install_recursive($rdocdir, ridatadir, :mode => $data_mode)
   end