--- src/Makefile.orig	2011-10-01 00:07:58.000000000 +0900
+++ src/Makefile	2011-10-01 00:08:17.000000000 +0900
@@ -12,8 +12,9 @@
 
 DEFINES=-DKANJI -DPICTURE -DHTML
 
-CC=gcc
-CFLAGS= -fwritable-strings ${DEFINES} -DBSD -DDEBUG -O2 -s
+CC?=gcc
+CFLAGS?= -fwritable-strings ${DEFINES} -DBSD -DDEBUG -O2 -s
+CFLAGS+= ${DEFINES}
 
 #CC=cc
 #CFLAGS= -O -fwritable-strings ${DEFINES} -DBSD -DDEBUG
@@ -33,8 +34,8 @@
 OBJS_KANJI=roffout.o analyze.o table.o title.o picture.o ftitle.o
 
 HDRS=plain2.h table.h picture.h kanji.h
-LIBS=
-LDFLAGS=
+LIBS?=
+LDFLAGS?=
 
 plain2: ${OBJS_NOKANJI} ${OBJS_KANJI}
 	${CC} ${CFLAGS} ${LDFLAGS} -o plain2 ${OBJS_NOKANJI} ${OBJS_KANJI} ${LIBES}