[exim] local users delivery broken

Hi all,

I have followed the procedure in

http://www.exim.org/exim-html-4.40/doc/html/FAQ_4.html#TOC148

that is, modifying

    data = ${lookup{$local_part}lsearch{/etc/aliases}}

to

    data = ${lookup{$local_part@$domain}lsearch{/etc/aliases}}

in order to allow domains on the left of my /etc/aliases. However I
think this may have broken local delivery - mail to root, postmaster,
anything without a domain in fails with "unrouteable address". What
have I missed?

Antony