pg_hba auth failure

pg_hba.conf entry:
host     all         all         192.168.0/24                        md5


I get the error
2004-06-14 20:51:48 [21072] LOG:  invalid entry in pg_hba.conf file at
line 89, token "md5"

When I connect as:
psql -U postfix -h 192.168.0.5 postfix

This user works locally with version 7.4.2.

Incompatable?