--- bsd.port.mk.ORI	2017-01-26 06:40:17.640910000 +0100
+++ bsd.port.mk	2017-01-30 09:26:16.108512000 +0100
@@ -1247,6 +1247,13 @@
 PORTDIRNAME?=	${_PORTDIRNAME}
 PKGORIGIN?=		${PKGCATEGORY}/${PORTDIRNAME}
 
+.if defined(EXTRA_PATCH_TREE)
+.if exists(${EXTRA_PATCH_TREE}/${PKGORIGIN}/Makefile.local)
+.include "${EXTRA_PATCH_TREE}/${PKGORIGIN}/Makefile.local"
+USE_SUBMAKE=	yes
+.endif
+.endif
+
 # where 'make config' records user configuration options
 PORT_DBDIR?=	/var/db/ports