removing "not null" modifier

Hello,

let's say I have created a postgresql-7.2.2 db using the following cmds:

CREATE TABLE status
(
id SERIAL NOT NULL PRIMARY KEY,
name VARCHAR(32)
);

CREATE TABLE event
(
id SERIAL NOT NULL PRIMARY KEY,
description VARCHAR(32),
status_id INTEGER NOT NULL REFERENCES status(id)
);

in psql I then see:

mydb=# \d event
Table "event"
Column | Type | Modifiers
-------------+-----------------------+--------------------------------------------------
id | integer | not null default nextval('"event_id_seq"'::text)
description | character varying(32) |
status_id | integer | not null
Primary key: event_pkey
Triggers: RI_ConstraintTrigger_43210

The question:

how can I get rid of the "not null" modifier on status_id?

thanks,

Robert Urban