diff --git a/ChangeLog b/ChangeLog
index 4e62997d5d..d41409044c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Nov 29 15:53:38 2012  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* ext/psych/extconf.rb: added --enable-bundled-libyaml option.  this
+	  enforces using bundled libyaml.
+
 Thu Nov 29 15:51:54 2012  Eric Hodel  <drbrain@segment7.net>
 
 	* lib/rubygems*:  Updated to RubyGems 2.0
diff --git a/ext/psych/extconf.rb b/ext/psych/extconf.rb
index bba3ab2c63..65e83a3554 100644
--- a/ext/psych/extconf.rb
+++ b/ext/psych/extconf.rb
@@ -6,7 +6,7 @@ require 'fileutils'
 
 dir_config 'libyaml'
 
-unless find_header('yaml.h') && find_library('yaml', 'yaml_get_version')
+if enable_config("bundled-libyaml", false) || !(find_header('yaml.h') && find_library('yaml', 'yaml_get_version'))
   # Embed libyaml since we could not find it.
 
   $VPATH << "$(srcdir)/yaml"