--- a/unix/Makefile	2008-05-07 14:33:56.000000000 +0800
+++ b/unix/Makefile	2023-04-16 16:14:10.611625606 +0800
@@ -22,7 +22,7 @@
 LN = ln -s
 
 # (to use the GNU compiler, change cc to gcc in CC)
-CC = cc
+CC ?= cc
 BIND = $(CC)
 AS = $(CC) -c
 CPP = /lib/cpp