Actress Carrie Fisher figures she has a good reason for finally revealing that she and her “Star Wars” co-star Harrison Ford were carrying on an affair while the sci-fi classic was filming in 1976.

People reports that Fisher’s reasoning is pretty simple: “It’s been 40 years!” Fisher, now 60, told the publication when asked why she dished about the affair in her new book, “The Princess Diarist.”

Fisher added: “I didn’t say anything to anybody for years but it’s not like anyone’s deeply affected by it anymore.”

People notes: “Whether Ford, a 33-year-old married father of two at the time, will agree remains to be seen. Fisher did give the actor (who didn’t respond to People’s request for comment) a friendly heads-up and even sent him a draft — but she doesn’t know if he’s even read it.”

The magazine interviewed Fisher in connection with its publication of an excerpt from “The Princess Diarist” in this week’s issue of People.

Fisher, who was 19 when she began her three-month affair with Ford, added: “Harrison’s very private, but I think I waited an appropriate amount of time. How much longer could I wait?”