Ambiguous error message

In PostgreSQL 7.4, the following select:

select texten, total
from (select protocolid, count(*) as total) from ips where catid=1     group by protocolid order by protocolid) as c
innerjoin protocols using (protocolid);
 

gives the error message:

ERROR:  subquery in FROM must have an alias
HINT:  For example, FROM (SELECT ...) [AS] foo.

Why isn't the "as c" considered as an alias?
 Sam
-- 
Samuel Tardieu -- sam@rfc1149.net -- http://www.rfc1149.net/sam