diff --git a/share/mk/src.libnames.mk b/share/mk/src.libnames.mk
--- a/share/mk/src.libnames.mk
+++ b/share/mk/src.libnames.mk
@@ -35,6 +35,10 @@
 		unbound \
 		zstd
 
+# Let projects based on FreeBSD append to _PRIVATELIBS
+# by maintaining their own LOCAL_PRIVATELIBS list.
+_PRIVATELIBS+=	${LOCAL_PRIVATELIBS}
+
 _INTERNALLIBS=	\
 		amu \
 		bsnmptools \
@@ -79,6 +83,10 @@
 		wpautils \
 		wpawps
 
+# Let projects based on FreeBSD append to _INTERNALLIBS
+# by maintaining their own LOCAL_INTERNALLIBS list.
+_INTERNALLIBS+=	${LOCAL_INTERNALLIBS}
+
 _LIBRARIES=	\
 		${_PRIVATELIBS} \
 		${_INTERNALLIBS} \