diff --git a/tools/build/mk/OptionalObsoleteFiles.inc b/tools/build/mk/OptionalObsoleteFiles.inc
--- a/tools/build/mk/OptionalObsoleteFiles.inc
+++ b/tools/build/mk/OptionalObsoleteFiles.inc
@@ -9214,6 +9214,7 @@
 OLD_FILES+=etc/periodic/daily/404.status-zfs
 OLD_FILES+=etc/periodic/daily/800.scrub-zfs
 OLD_FILES+=etc/zfs/exports
+OLD_DIRS+=etc/zfs/compatibility.d
 OLD_DIRS+=etc/zfs
 OLD_LIBS+=lib/libavl.so.2
 OLD_LIBS+=lib/libnvpair.so.2