diff --git a/Makefile b/Makefile
index dc1ba7a..239a21b 100644
--- a/Makefile
+++ b/Makefile
@@ -15,21 +15,7 @@
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301	 USA
 
-ifndef KDIR
-KDIR = /lib/modules/$(shell uname -r)/build
-endif
-ifneq "t" "$(shell test -e ${KDIR}/include/linux/stddef.h && echo t)"
-$(error incorrect KDIR)
-endif
-
-ifndef ARCH
-ARCH := $(shell uname -m)
-endif
-ARCH := $(shell echo ${ARCH} | sed -e 's/_64$$//')
-ArchDir = ${KDIR}/arch/${ARCH}/include
-
-CFLAGS += -I${KDIR}/include -I./libau
-CFLAGS += $(shell test -d ${ArchDir} && echo -I${ArchDir})
+CFLAGS += -I./libau
 CFLAGS += -O -Wall
 
 Cmd = umount.aufs auchk aubrsync
diff --git a/README b/README
index f1240e5..a95196d 100644
--- a/README
+++ b/README
@@ -9,17 +9,21 @@ And these are not for aufs1 essentially, except aubrsync. See below in
 detail.
 
 Makefile in this tree has some customizable make-variables.
-- KDIR
-  specify your kernel source path if necessary.
-  Note: this path should point kernel _source_ path, instead of kernel
-  _build_ path. Don't confuse with the path in "make O=<kdir>" when you
-  build a kernel in a different dir.
-- CPPFLAGS or ARCH
-  specify the include path to your aufs2-standalone tree, if necessary.
-  the makefile finds the correct ${KDIR}/arch/${ARCH}/include dir and
-  sets the include path to CPPFLAGS="-I...". if the logic in Makefile is
-  poor and doesn't support your build environment, then set the
-  variables directly.
+- CPPFLAGS
+  specify the include path if necessary.
+  Some of linux kernel header files are necessary including
+  linux/aufs_type.h. If you have installed kernel header files to
+  /usr/include, then you may not need to specify CPPFLAGS.
+  Otherwise you need to do something like this sample.
+  + run "make headers_install" in your kernel source tree, and
+    $LinuxSrc/usr/include is created and header files are installed
+    there.
+  + if you build aufs2 as module from aufs2-standalone.git, then
+    $Aufs2Stdalone/usr/include is created and header files are
+    installed there.
+  + and specify
+	CPPFLAGS="-I $LinuxSrc/usr/include -I $Aufs2Stdalone/usr/include"
+
 - DESTDIR
   specify your install path if necessary.
   some commands have to be installed under /sbin.