diff --git a/en_US.ISO8859-1/books/handbook/disks/chapter.xml b/en_US.ISO8859-1/books/handbook/disks/chapter.xml
index e5ca67e5bf..f91b3484a0 100644
--- a/en_US.ISO8859-1/books/handbook/disks/chapter.xml
+++ b/en_US.ISO8859-1/books/handbook/disks/chapter.xml
@@ -2123,7 +2123,7 @@ Filesystem 1K-blocks Used Avail Capacity  Mounted on
 	  file system.  To &man.mount.8; the snapshot
 	  <filename>/var/snapshot/snap</filename> run:</para>
 
-	<screen>&prompt.root; <userinput>mdconfig -a -t vnode -f /var/snapshot/snap -u 4</userinput>
+	<screen>&prompt.root; <userinput>mdconfig -a -t vnode -o readonly -f /var/snapshot/snap -u 4</userinput>
 &prompt.root; <userinput>mount -r /dev/md4 /mnt</userinput></screen>
       </listitem>
     </itemizedlist>