Hayden Christensen and Rachel Bilson Photo by: Dimitrios Kambouris / WireImage
Rachel Bilson and Hayden Christensen Are Engaged

Rachel Bilson and her longtime beau, Hayden Christensen, got engaged quietly over the holidays, PEOPLE has learned.

According to a friend of the actress, the two, who costarred in 2008's Jumper, got engaged in December.

"They're so excited," says the pal, adding that no wedding date has been set. "They're a great couple. Rachel seems thrilled beyond belief."

When contacted, Bilson's rep told PEOPLE, "I don't comment on my clients' personal lives."

A rep for Christensen had no comment.

The engagement news was first reported by the New York Post's Page Six.