--- Makefile.orig	2015-06-10 21:49:31 UTC
+++ Makefile
@@ -1,7 +1,7 @@
 # All the actual Makefiles are deeper in the directory tree.  
 # I am just calling them, here.
 
-PREFIX=/usr
+PREFIX?=/usr
 DESTDIR=
 UNAME_S := $(shell uname -s)