Zack Snyder recently revealed that he sought and received Christopher Nolan’s blessing for Batman v Superman: Dawn of Justice (though it really sounded like Nolan just didn’t care), but he wasn’t the only one looking for approval for the upcoming superhero epic. Ben Affleck says that he also went to his Batman predecessors — not for their blessing, but for some helpful Bat-tips.

In an interview with Good Morning America, Affleck says he spoke with previous Batmen Christian Bale and George Clooney, who both offered the actor some advice for playing Bruce Wayne / The Dark Knight. Affleck wouldn’t reveal what advice he received from Clooney, only offering that “he had some advice which is not repeatable.” You can make of that what you will, but let’s just imagine that Clooney told Affleck to make sure his costume didn’t have Bat-nipples.

As for Bale, he told the new Batman to ensure that his suit had a zipper, and while Affleck wouldn’t say why, it seems pretty obvious. You can watch Affleck and Henry Cavill’s full interview below:

WATCH: “I talked to George Clooney who had some advice that’s not repeatable.” Ben Affleck and Henry Cavill talk Batman v Superman: Dawn of Justice - advice from superheroes of the past, Michael Keaton, Val Kilmer, Christian Bale and explain the bad blood between Batman and Superman. Posted by Good Morning America on Tuesday, February 16, 2016

Batman v Superman: Dawn of Justice also stars Gal Gadot as Wonder Woman and Jesse Eisenberg as Lex Luthor, with Man of Steel stars Amy Adams, Laurence Fishburne and Diane Lane. The film arrives on March 25.