--- ./GNUmakefile.orig	2021-09-07 19:57:19.175164197 +0000
+++ ./GNUmakefile	2021-09-07 19:57:28.528497597 +0000
@@ -3,7 +3,7 @@
 ############################################################################
 
 # Set this to change the target installation path
-PREFIX   = /usr/local
+PREFIX  ?= /usr/local
 BINDIR   = ${PREFIX}/bin
 SHAREDIR = ${PREFIX}/share
 MANDIR   = ${SHAREDIR}/man