diff --git a/howto/retire-a-host.md b/howto/retire-a-host.md
index 65c02e8fd5d8c0270bb370a02a887f777b0a33f2..0b579dbeed99ad742cfa9473b9c884419182ca13 100644
--- a/howto/retire-a-host.md
+++ b/howto/retire-a-host.md
@@ -185,13 +185,18 @@ When you return:
  7. wipe the remaining disk and shutdown:
 
         # hit control-a control-g to enable the bell in screen
-        nwipe --autonuke --method=random --verify=off /dev/nbd0 ; \
+        wipefs -af /dev/noop3 &&
+        wipefs -af /dev/noop && \
+        nwipe --autonuke --method=random --verify=off /dev/noop ; \
         printf "SHUTTING DOWN FOREVER IN ONE MINUTE\a\n" ; \
         sleep 60 ; \
         echo o > /proc/sysrq-trigger ; \
         sleep 60 ; \
         echo b > /proc/sysrq-trigger ; \
 
+    Note: as a safety precaution, the above device has been replaced
+    by `noop`, that should be (say) `sda` instead.
+
 A few tricks if nothing works in the shell which might work in a case
 of an emergency: