--- Makefile.orig	2020-08-08 10:38:31 UTC
+++ Makefile
@@ -1,6 +1,6 @@
-MANDIR=/usr/local/share/man/man1
+MANDIR?=/usr/local/share/man/man1
 
-INSTALL_FLAGS=-m 0755 -p -D
+INSTALL_FLAGS?=-m 0755 -p -D
 
 #detect Mac OS X
 UNAME=$(shell uname -s)