Benedict Cumberbatch (Shizuo Kambayashi/AP)

Benedict Cumberbatch blew the surprise and revealed he and Martin Freeman will make a fourth season of PBS’s “Sherlock.”

“We’ve agreed to two more [seasons] but I could get into trouble for saying that,” Cumberbatch said in an interview this week with RadioTimes.

“All I know at the moment is I’m doing these three [episodes for Season 3] and another three [for Season 4].”

(On the PBS version of the Sherlock Holmes story, three episodes is all you get per season, compared to more than 20 per season on the CBS version of the franchise.)

Cumberbatch suggested he’d be open to more seasons beyond a fourth, though it depends on his availability and Freeman’s. Freeman has another gig as Bilbo Baggins in the Hobbit flick franchise and Cumberbatch is about to make his big-screen debut on JJ Abrams’ latest “Star Trek” update.

PBS hasn’t yet set a date for the third “Sherlock” season.