-Wl,-rpath seems to be more portable than -R

src/Makefile

@@ -7,7 +7,7 @@ CC	= cc
 CPPFLAGS=
 CFLAGSF	= -W
 CFLAGS	= -Wall -g -O2
-LDFLAGS	= -L $(PREFIX)/lib -R $(PREFIX)/lib -l System 
+LDFLAGS	= -L $(PREFIX)/lib -Wl,-rpath,$(PREFIX)/lib -l System 
 RM	= rm -f
 MKDIR	= mkdir -p
 INSTALL	= install

src/project.conf

@@ -1,7 +1,7 @@
 targets=configure
 cflags_force=-W
 cflags=-Wall -g -O2
-ldflags=-L $(PREFIX)/lib -R $(PREFIX)/lib -l System -l dl
+ldflags=-L $(PREFIX)/lib -Wl,-rpath,$(PREFIX)/lib -l System -l dl
 dist=Makefile,configure.h,makefile.h,settings.h
 
 [configure]