The latest issue of DC’s Action Comics has confirmed that Marvel is part of their multiverse.

DC and Marvel may be rival comic book publishers, but they have a long tradition of making subtle continuity nods to one another. The last few weeks have seen some surprising references, with Infinity Countdown Prime #1 even suggesting DC’s Captain Marvel exists in Marvel’s multiverse. This week sees DC return the favor, in Action Comics #998.

The current arc has seen Superman travel in time, attempting to learn whether or not his father truly did survive Krypton’s destruction. His attempt to investigate caused serious damage to the timestream; this has only been repaired thanks to the intervention of Booster Gold. The two have proved to be a formidable team, blasted to the future for an encounter with General Zod. In Action Comics #998, Booster and Superman escape into the timeship, and Booster jokingly refers to his AI Skeets as “Alfred.” Needless to say, Skeets objects to being named after Batman’s butler, and Booster responds:

“Not like I can call you Jarvis. Whole other timeline.”

It’s a tremendously effective pun. In the comics, Jarvis is the Avengers’ butler (essentially Marvel’s version of Alfred). In the movies, of course, Jarvis is actually Tony Stark’s personal Artificial Intelligence. So the joke works on two different levels. It’s also an amusing hint that Marvel’s heroes exist somewhere in DC’s comic book multiverse as well.

This is hardly the first time Marvel and DC have crossed over. Sometimes the links have been subtle (including an unauthorized crossover courtesy of Gerry Conway, Steve Englehart and Len Wein). Other times, they’ve been overt - most famously in 1996’s DC Versus Marvel miniseries. That revealed the two multiverses are “twins,” powerful gods who - in the crossover - came into opposition with one another. The miniseries famously saw fans vote on who would win in various face-offs, including Superman versus the Hulk, Wolverine versus Lobo, and Storm versus Wonder Woman. Amusingly, it also featured a random romance between the X-Men’s Jubilee and Robin.

What is more surprising, though, is that both Marvel and DC have dropped fairly high-profile nods to the other publisher in the space of a fortnight. Action Comics is DC’s tentpole Superman book, after all; Infinity Countdown #1, meanwhile, is the latest Marvel event. It’s tempting to speculate that another inter-publisher crossover is on the cards, but the reality is more likely that relations between Marvel and DC are in a good place right now. As a result, both publishers feel willing to have a bit of fun.

MORE: Which Superheroes Are Marvel and Which are DC?

You can buy Action Comics #998 online or in store now.