diff --git a/ChangeLog b/ChangeLog
index 9643dd1df0..976083fe6f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Thu Apr  7 23:58:40 2005  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/extmk.rb (extmake): keep directory names in Makefile as macros.
+
+	* lib/mkmf.rb (configuration, create_makefile): ditto.
+
+	* lib/mkmf.rb (CXX_EXT): separate C++ extensions.
+
 Thu Apr  7 17:24:17 2005  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* eval.c (rb_call0): "return" event hook should be always executed
@@ -18,7 +26,7 @@ Thu Apr  7 11:49:53 2005  Kouhei Sutou  <kou@cozmixng.org>
 
 	* test/rss/test_maker_dc.rb (test_rss10_multiple): added a test
 	  for making multiple Dublin Core items.
-	
+
 Wed Apr  6 16:06:30 2005  Hirokazu Yamamoto  <ocean@m2.ccsnet.ne.jp>
 
 	* test/ruby/test_env.rb (test_key): should test ENV.key instead of
@@ -57,19 +65,19 @@ Tue Apr  5 15:15:26 2005  Kouhei Sutou  <kou@cozmixng.org>
 
 	* lib/rss/trackback.rb (RSS::TrackBackUtils.new_with_value_if_need):
 	  moved to RSS::Utils.
-	
+
 	* lib/rss/utils.rb (RSS::Utils.new_with_value_if_need):
 	  moved from RSS::TrackBackUtils.
-	
+
 
 	* lib/rss/maker/image.rb: fixed invalid argument of
 	  add_need_initialize_variable bug.
-	
+
 	* lib/rss/maker/trackback.rb: ditto.
 
 
 	* lib/rss/rss.rb (Hash#merge): added for ruby 1.6.
-	
+
 	* lib/rss/rss.rb (RSS::BaseModel.date_writer): changed to accept nil
 	  for date value.
 
diff --git a/ext/extmk.rb b/ext/extmk.rb
index db4bdf3ce0..d7d4d2fbd2 100644
--- a/ext/extmk.rb
+++ b/ext/extmk.rb
@@ -102,6 +102,8 @@ def extmake(target)
     Dir.chdir target
     top_srcdir = $top_srcdir
     topdir = $topdir
+    mk_srcdir = CONFIG["srcdir"]
+    mk_topdir = CONFIG["topdir"]
     prefix = "../" * (target.count("/")+1)
     $hdrdir = $top_srcdir = relative_from(top_srcdir, prefix)
     $topdir = prefix + $topdir
@@ -115,6 +117,9 @@ def extmake(target)
     unless $ignore
       Config::CONFIG["srcdir"] = $srcdir
       Config::CONFIG["topdir"] = $topdir
+      CONFIG["hdrdir"] = ($hdrdir == top_srcdir) ? top_srcdir : "$(topdir)/"+top_srcdir
+      CONFIG["srcdir"] = "$(hdrdir)/ext/#{$mdir}"
+      CONFIG["topdir"] = $topdir
       begin
 	if (!(ok &&= extract_makefile(makefile)) ||
 	    !(t = modified?(makefile, MTIMES)) ||
@@ -140,14 +145,12 @@ def extmake(target)
 	rm_f "conftest*"
 	config = $0
 	$0 = $PROGRAM_NAME
-	Config::CONFIG["srcdir"] = $top_srcdir
-	Config::CONFIG["topdir"] = topdir
       end
     end
     ok = yield(ok) if block_given?
     unless ok
       open(makefile, "w") do |f|
-	f.print dummy_makefile($srcdir)
+	f.print dummy_makefile(CONFIG["srcdir"])
       end
       return true
     end
@@ -175,6 +178,10 @@ def extmake(target)
     end
   ensure
     Config::CONFIG["srcdir"] = $top_srcdir
+    Config::CONFIG["topdir"] = topdir
+    CONFIG["srcdir"] = mk_srcdir
+    CONFIG["topdir"] = mk_topdir
+    CONFIG.delete("hdrdir")
     $hdrdir = $top_srcdir = top_srcdir
     $topdir = topdir
     Dir.chdir dir
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 5e83eb76b2..841e79c0af 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -8,10 +8,11 @@ require 'shellwords'
 CONFIG = Config::MAKEFILE_CONFIG
 ORIG_LIBPATH = ENV['LIB']
 
-SRC_EXT = %w[c cc m cxx cpp]
+CXX_EXT = %w[cc cxx cpp]
 if /mswin|bccwin|mingw|msdosdjgpp|human|os2/ !~ CONFIG['build_os']
-  SRC_EXT.concat(%w[C])
+  CXX_EXT.concat(%w[C])
 end
+SRC_EXT = %w[c m] << CXX_EXT
 $static = $config_h = nil
 
 unless defined? $configure_args
@@ -847,8 +848,8 @@ SHELL = /bin/sh
 #### Start of system configuration section. ####
 
 srcdir = #{srcdir}
-topdir = #{$topdir}
-hdrdir = #{$extmk ? $hdrdir : '$(topdir)'}
+topdir = #{$extmk ? CONFIG["topdir"] : $topdir}
+hdrdir = #{$extmk ? CONFIG["hdrdir"] : '$(topdir)'}
 VPATH = #{vpath.join(CONFIG['PATH_SEPARATOR'])}
 }
   drive = File::PATH_SEPARATOR == ';' ? /\A\w:/ : /\A/
@@ -938,7 +939,7 @@ def create_makefile(target, srcprefix = nil)
     target_prefix = ""
   end
 
-  srcprefix ||= '$(srcdir)'
+  srcprefix ||= CONFIG['srcdir']
   Config::expand(srcdir = srcprefix.dup)
 
   if not $objs
@@ -979,7 +980,7 @@ def create_makefile(target, srcprefix = nil)
   dllib = target ? "$(TARGET).#{CONFIG['DLEXT']}" : ""
   staticlib = target ? "$(TARGET).#$LIBEXT" : ""
   mfile = open("Makefile", "wb")
-  mfile.print configuration(srcdir)
+  mfile.print configuration(srcprefix)
   mfile.print %{
 libpath = #{$LIBPATH.join(" ")}
 LIBPATH = #{libpath}
@@ -1058,7 +1059,7 @@ site-install-rb: install-rb
   mfile.print ".SUFFIXES: .#{SRC_EXT.join(' .')} .#{$OBJEXT}\n"
   mfile.print "\n"
 
-  %w[cc cpp cxx C].each do |ext|
+  CXX_EXT.each do |ext|
     COMPILE_RULES.each do |rule|
       mfile.printf(rule, ext, $OBJEXT)
       mfile.printf("\n\t%s\n\n", COMPILE_CXX)