[SQL] date question

[Judith Altamirano Figueroa]

Hi everybody, in Postgres 7.0.2 I have the next query:

SELECT * from clientes_proceso where fecha_mod::date <= now() -1;

but in version 8.0.1 returns the next error:

ERROR: The operator doesn't exist: timestamp with time zone - integer

How can drop a day to now()??