--- C/Makefile.orig	2024-06-24 00:49:39 UTC
+++ C/Makefile
@@ -42,7 +42,7 @@ TEST = test
 ###
 # installation options
 #
-prefix = /usr/local
+prefix ?= /usr/local
 PREFIX = $(prefix)
 BINDIR = $(PREFIX)/bin
 DATADIR = $(PREFIX)/share