diff --git a/etc/mtree/README b/etc/mtree/README
index 2ab10e861044..8e3b74fc3387 100644
--- a/etc/mtree/README
+++ b/etc/mtree/README
@@ -1,5 +1,7 @@
 $FreeBSD$
 
+# Note: If you modify these files, please keep hier(7) updated!
+
 These files are used to create empty file hierarchies for building the
 system into.  Some notes about working with them are placed here to try
 and keep them in good working order.