diff --git a/sbin/reboot/reboot.8 b/sbin/reboot/reboot.8
index 6833fdd213a3..5fee3ece7c67 100644
--- a/sbin/reboot/reboot.8
+++ b/sbin/reboot/reboot.8
@@ -144,7 +144,10 @@ After changing vfs.root.mountfrom with
 can be used to change the root filesystem while preserving kernel state.
 This requires the
 .Xr tmpfs 5
-kernel module to be loaded.
+kernel module to be loaded because
+.Xr init 8
+needs a place to store itself after the old root is unmounted, but
+before the new root is in place.
 .El
 .Pp
 The