--- makefile.unx.orig	1996-03-05 06:36:27.000000000 +0900
+++ makefile.unx	2013-10-19 20:15:02.149614385 +0900
@@ -7,9 +7,13 @@
 # To use, enter "make -f makefile.unx"
 
 RM=rm -f
-CC=gcc
+CC=cc
 CFLAGS=-O -Wall -DUNIX -DUSE_REMINDER
 
+.ifdef PREFIX
+CFLAGS+=-DPREFIX="\"${PREFIX}\""
+.endif
+
 BINDIR=/usr/bin
 MANDIR=/usr/man