The Killing Joke was one of the key Batman graphic novels of the 1980s–alongside The Dark Knight Returns, its influence is still being felt in depictions of the characters today. An animated adaptation of Alan Moore and Brian Bolland’s dark tale of Batman and The Joker was first announced last year, and is due for release later in 2016. It has now been confirmed that it has been given an R rating.

As reported by EW, the upcoming film is the first in Warner’s ‘DC Universe Original Movie’ franchise to be given the restrictive certificate from the MPAA. It joins the recent live-action movie Batman v Superman: Dawn of Justice, which will also carry an R rating once the extended version hits home video.

Sam Register, president of Warner Bros Animation, confirmed the rating in a statement. “From the start of production, we encouraged producer Bruce Timm and our team to remain faithful to the original story–regardless of the eventual MPAA rating,” he said. “The Killing Joke is revered by the fans, particularly for its blunt, often-shocking adult themes and situations.

“We felt it was our responsibility to present our core audience–the comics-loving community–with an animated film that authentically represented the tale they know all too well.”

The Killing Joke has been made by the team behind the acclaimed ’90s show Batman: The Animated Series, with Kevin Conroy and Mark Hamill reprising their roles as the Caped Crusader and The Joker. Twin Peaks star Ray Wise plays Commissioner Gordon, with Tara Strong as his daughter Barbara (aka Batgirl).

Batman: The Killing Joke is to premiere at the San Diego Comic-Con in July, before hitting home entertainment platforms later in the year.