Let’s face it: the odds of another Back to the Future movie happening are slim, at least during the lifetimes of filmmakers Robert Zemeckis and Bob Gale. But just in case they have a change of heart and decide that a Back to the Future 4 is a good idea after all, there’s at least one member of the original cast who will gladly show up for more. Christopher Lloyd, who embodied the time traveling scientist Dr. Emmett “Doc” Brown in the original trilogy, appeared at Niagara Falls Comic Con last month and spoke about his idea for a fourth film in the franchise.

ComicBook.com reports that at the convention, Lloyd said he would be “happy” to reprise his role again in a new movie, but that the theoretical fourth film would need to have a universal message:

“I think somehow it needs to kind of convey a message about something that’s important to everyone, universally, like climate change. Some way of incorporating whatever fever is going on at the moment into the film and keep the feeling of one, two and three. That’s a tricky, tricky deal. Because you don’t want to do another one and disappoint. So I don’t know. I’d be happy to, for myself. But we’ll see.”

This isn’t the first time he’s mentioned climate change as a possible topic for the sequel. In a 2015 interview with USA Today, Lloyd said, “There’s always the danger of sequels not living up to the original, so it’d have to be something momentous and current: dealing with ISIS or climate change or something radical and have a real urgency to it,” so this has been on his mind for several years.

As for Michael J. Fox, Lloyd seemed to imply that his co-star might also be interested in a potential return (echoing a sentiment he also voiced back in 2015):

“His Parkinson’s, he has it, but it’s kind of, ‘So what?’ He just moves ahead. It’s very cool. A couple months ago there was like a bunch of us, Back to the Future [cast], Tom Wilson and Lea Thompson…we had a panel with all of us, and Michael just goes forth and talks, breaks people up, so it’s very cool.”

Last year, Lloyd said he’d only be interested in coming back for a fourth movie if Zemeckis and Gale were on board and excited about it…the only problem, of course, is that they aren’t. Not only that, but they’re actively against the idea of bringing this franchise back to life. In 2016, Zemeckis spoke with an Italian news outlet and his answer to a question about a possible fourth movie is translated like this: “There will never ever be a Return to the Future in the most absolute way 4. There will be no more Back to the Future.” The translation obviously isn’t perfect, but there’s not much lost in it, either – it’s pretty clear we’re not going to be seeing an 80-year-old Doc Brown reuniting with a 58-year-old Marty McFly any time soon, and as much as some fans might want it, we’re almost certainly better off this way.

But at least we can revel in the glory of this clip featuring Lloyd playing Doc Brown once again in The Earth Day Special from 1990: