Index: devel/mdb/Makefile
===================================================================
--- devel/mdb/Makefile
+++ devel/mdb/Makefile
@@ -25,6 +25,8 @@
 WRKSRC_SUBDIR=	freebsd/cddl/usr.bin/mdb
 CFLAGS+=	-DMDB_PREFIX=\\\"${PREFIX}\\\" -g
 
+.include <bsd.port.pre.mk>
+
 .if !exists(${SRC_BASE}/cddl/compat) || !exists(${SRC_BASE}/sys/cddl/compat)
 IGNORE=		requires full source tree with CDDL sources
 .endif