--- makefile.old	Wed Jul  7 02:03:58 1999
+++ makefile	Wed Jul  7 02:04:19 1999
@@ -6,11 +6,11 @@
 	 refute.o unify.o defsysp.o syspred1.o\
 	 syspred2.o trans.o tr_sub.o tr_split.o
 #CFLAGS = -g
-CFLAGS = -pg -g      # for debug
+CFLAGS?= -pg -g      # for debug
 #CFLAGS = -O2        # for optimization
 #CFLAGS = -O4
 #CC = gcc
-CC = cc
+CC?= cc
 FLAGS = -lm
 
 cup: $(OBJECTS)