diff --git a/ChangeLog b/ChangeLog
index fa7e9ef16e..11b0c6e842 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Jun  1 15:40:46 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* tool/rbinstall.rb (gem): fix for rubygems change.
+
 Wed Jun  1 14:07:57 2011  Ryan Davis  <ryand-ruby@zenspider.com>
 
 	* lib/minitest/*: MOSTLY Imported minitest 2.2.1 (r6277)... One
diff --git a/tool/rbinstall.rb b/tool/rbinstall.rb
index 6234f6fe47..f0a08b8ebd 100755
--- a/tool/rbinstall.rb
+++ b/tool/rbinstall.rb
@@ -532,14 +532,10 @@ install?(:local, :comm, :man) do
 end
 
 install?(:ext, :comm, :gem) do
-  directories = []
-  IO.foreach(File.join(srcdir, "lib/rubygems.rb")) do |line|
-    if /^\s*DIRECTORIES\s*=\s*%w\[(.*?)\]/ =~ line
-      directories = $1.split
-      break
-    end
-  end
-  gpath = CONFIG["sitelibdir"].sub(%r'/site_ruby/(?=[^/]+)', '/gems/')
+  $:.unshift(File.join(srcdir, "lib"))
+  require("rubygems.rb")
+  gpath = Gem.default_dir
+  directories = Gem.ensure_gem_subdirectories(gpath)
   prepare "default gems", gpath, directories
 
   destdir = File.join(gpath, directories.grep(/^spec/)[0])