diff --git a/ChangeLog b/ChangeLog
index b3ee143272..6416630374 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jul 14 06:02:26 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/optparse.rb (OptionParser#environment): requires shellwords.
+	  [ruby-dev:35466]
+
 Sun Jul 13 21:23:08 2008  Masaki Suketa  <masaki.suketa@nifty.ne.jp>
 
 	* ext/win32ole/win32ole.c (EVENTSINK_Invoke): using hash
diff --git a/lib/optparse.rb b/lib/optparse.rb
index c6a54ef30a..86681235a0 100644
--- a/lib/optparse.rb
+++ b/lib/optparse.rb
@@ -1474,6 +1474,7 @@ class OptionParser
   #
   def environment(env = File.basename($0, '.*'))
     env = ENV[env] || ENV[env.upcase] or return
+    require 'shellwords'
     parse(*Shellwords.shellwords(env))
   end