diff --git a/ChangeLog b/ChangeLog
index e80afef5d9..49cd4f8ba9 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 21:09:02 2008  Koichi Sasada  <ko1@atdot.net>
 
 	* bootstraptest/test_knownbug.rb -> ./test_knownbug.rb: moved.
diff --git a/enc/Makefile.in b/enc/Makefile.in
index cafeff964a..436c0f4e32 100644
--- a/enc/Makefile.in
+++ b/enc/Makefile.in
@@ -27,6 +27,10 @@ CC = @CC@
 OUTFLAG = @OUTFLAG@$(empty)
 COUTFLAG = @COUTFLAG@$(empty)
 CFLAGS = $(CCDLFLAGS) @CFLAGS@ @ARCH_FLAG@
+cflags = @cflags@
+optflags = @optflags@
+debugflags = @debugflags@
+warnflags = @warnflags@
 CCDLFLAGS = @CCDLFLAGS@
 INCFLAGS = -I. -I$(arch_hdrdir) -I$(hdrdir) -I$(top_srcdir)
 DEFS = @DEFS@
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index b63dfb857d..74a20609b2 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -1345,6 +1345,10 @@ OUTFLAG = #{OUTFLAG}
 COUTFLAG = #{COUTFLAG}
 
 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']}