diff --git a/handbook/computing/keyexchange.html b/handbook/computing/keyexchange.html
index 50968ddbc..234db7d69 100644
--- a/handbook/computing/keyexchange.html
+++ b/handbook/computing/keyexchange.html
@@ -62,7 +62,7 @@
 
 
 <h2>Your second machine</h2>
-<p>OK, you have an uploaded and usable key and you can ssh into the expo server. Now you want to set up a key for another machine such as your phone. You don't need a nerd admin now, you can do this yorself.
+<p>OK, you have an uploaded and usable key and you can ssh into the expo server. Now you want to set up a key for another machine such as your phone. You don't need a nerd admin now, you can do this yourself. But be <b>extremely careful</b> to follow this exactly. If you innocently rename the files to something that appears more sensible it won't work.
 <ol>
 <li>On your new machine, generate a key-pair. Since you are probably using a different operating system on your second machine, read the instructions above for the relevant OS. Yes you will be generating a new key. Do not re-use the key you had already.
 <li>This time though, you will want to be sure that the key has a meaningful label. On Linux this means something like this:
@@ -71,12 +71,13 @@
 <li>
 If you accepted the defaults, the public key will be called <span style="font-family:monospace; size=x-small; background-color: lightgray">id_rsa.pub</span> and it will be in <span style="font-family:monospace; size=x-small; background-color: lightgray">~/.ssh/</span> - check that this is the case.
 <li>Now copy the public key file to your <em>first machine</em>, the one that is already set up with a working key exchange with the expo server. Using email to yourself is easiest.
-<li>Rename the public key file to something that won't be confused with anyone else's key file, to e.g. <span style="font-family:monospace; size=x-small; background-color: lightgray">anathema-id_rsa.pub</span>
-<li>Now upload the public key using sFTP to <span style="font-family:monospace; size=x-small; background-color: lightgray">expo.survex.com/home/expo/.ssh/keys/</span>
-<li>Now login to the expo server on your first machine and do these commands:
+<li>Now upload the public key using sFTP (Filezilla configured to use sFTP, which uses Pageant by default) to <span style="font-family:monospace; size=x-small; background-color: lightgray">expo.survex.com/home/expo/.ssh/keys/</span>
+<li>Now login to the expo server on your first machine and do these commands:<br>
+Be <b>extremely careful</b> to type ">>" and not ">" in the fourth line below otherwise you will delete everything.
 <tt><font color=red">$</font> ssh expo@expo.survex.com
 <br><font color=blue">expo@expo:~$</font> cd .ssh
-<br><font color=blue">expo@expo:~/.ssh$</font> cat keys/anathema-id_rsa.pub >>authorized_keys
+<br><font color=blue">expo@expo:~$</font> cp -p authorized_keys authorized_keys.backup
+<br><font color=blue">expo@expo:~/.ssh$</font> cat keys/id_rsa.pub >>authorized_keys
 <br><font color=blue">expo@expo:~/.ssh$</font> ./list-keys.sh 
 <br><font color=blue">expo@expo:~/.ssh$</font> cat list-of-key-owners
 </tt>