diff -Nur sinit-1.0-orig/config.mk sinit-1.0/config.mk
--- sinit-1.0-orig/config.mk	2015-06-16 11:37:07.000000000 +0200
+++ sinit-1.0/config.mk	2016-07-13 10:24:25.952000000 +0200
@@ -2,10 +2,10 @@
 VERSION = 1.0
 
 # paths
-PREFIX = /usr/local
+PREFIX ?= /usr/local
 MANPREFIX = $(PREFIX)/share/man
 
-CC = cc
+CC ?= cc
 LD = $(CC)
 CPPFLAGS =
 CFLAGS   = -Wextra -Wall -Os