Actress Jennifer Aniston and her fiance Justin Theroux have reportedly locked in the date to get married.

"It's really happening! Jen is excited beyond belief. She says it will be the best day of her life," okmagazine.com quoted a source as saying.

Despite having decided on a date and venue, the "Friends" star, who was previously married to actor Brad Pitt, has decided to remain tight-lipped about the nuptials.

"If you try asking, she'll change the subject to keep everybody guessing," the source added.

The couple, who got engaged in August 2012, are said to be planning to keep the marriage a low-key affair.

"Neither of them wants a huge, glitzy wedding," said the source.