--- Makefile.orig	2024-08-23 12:01:44 UTC
+++ Makefile
@@ -54,7 +54,7 @@ HAS_REGEX=-DHAS_REGEX
 ### installdir    
 ###   will use $INSTDIR/bin  and  $INSTDIR/man/man1, 
 ###   both dirs have to exist for installation
-INSTDIR=/usr/local
+INSTDIR=${PREFIX}
 
 ### ------------------------------------------------------------------------
 ### --- end of user settings -----------------------------------------------