diff -ruN --exclude=CVS /usr/ports/graphics/netpbm/files/Makefile.config.FreeBSD ./files/Makefile.config.FreeBSD
--- /usr/ports/graphics/netpbm/files/Makefile.config.FreeBSD	2013-01-14 17:57:08.000000000 +0100
+++ ./files/Makefile.config.FreeBSD	2013-03-24 16:02:13.000000000 +0100
@@ -23,7 +23,7 @@
 
 STRIPFLAG = -s
 
-SYMLINK = ln -s
+SYMLINK = ln -sf
 
 MANPAGE_FORMAT = nroff