diff --git a/ChangeLog b/ChangeLog
index b640c71ba3..daf95d905f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Jun  9 21:14:26 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/mkmf.rb (configuration): set flags.
+
 Mon Jun  9 17:56:30 2008  Akinori MUSHA  <knu@iDaemons.org>
 
 	* lib/set.rb (Set#delete_if): Call to_a.
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index a532b5c0a8..2207be3ca5 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -1290,6 +1290,10 @@ LIBRUBYARG_SHARED = #$LIBRUBYARG_SHARED
 LIBRUBYARG_STATIC = #$LIBRUBYARG_STATIC
 
 RUBY_EXTCONF_H = #{$extconf_h}
+cflags   = #{CONFIG['cflags']}
+optflags = #{CONFIG['optflags']}
+debugflags = #{CONFIG['debugflags']}
+warnflags = #{CONFIG['warnflags']}
 CFLAGS   = #{$static ? '' : CONFIG['CCDLFLAGS']} #$CFLAGS #$ARCH_FLAG
 INCFLAGS = -I. #$INCFLAGS
 DEFS     = #{CONFIG['DEFS']}