Shawn Levy was determined to make Hugh Jackman's Wolverine suit comic-accurate for 'Deadpool 3'.
The 55-year-old filmmaker and his team went through "multiple, multiple, multiple iterations and fittings" to make sure the character's distinctive yellow costume was recognisable from his origins because he is unsure when, or even if, Wolverine will ever be on screen again.
He told Entertainment Weekly: "Like the rest of the world, I've waited two decades to see Wolverine in a whole movie with Deadpool, and I don't know if this is our last shot at Wolverine on screen, so I was going to make goddamned sure we get the old yellow and blue just once, and that we get it right."
And he joked he knew he had the right people on board to ensure they got the outfit right.
He laughed: "It also helps that I'm making this movie within the MCU, so I have access to an army of the nerdiest nerds available to a Marvel project.
Photos from the set of the film leaked earlier this year, showing Hugh in his yellow outfit next to Ryan Reynolds as Deadpool, and Shawn is happy with fan reaction so far.
He said: "Fortunately, it seems global reaction to those costumes has been overwhelmingly positive, so all's well that ends well."
And the director noted he knew location filming meant there would be a risk of leaks but he and Ryan "wanted our movie to be grounded and not feel like a bunch of physical environments filmed on a soundstage."
While the likes of Emma Corrin, Rob Delaney and Morena Baccarin are confirmed to be part of the movie - which is currently on hiatus due to the ongoing Hollywood strikes - there are unconfirmed rumours that Jennifer Garner will reprise her 2005 role as Elektra and Liev Schreiber will play Sabretooth, and the director refused to confirm or deny the speculation.
He teased: "I'd rather not weigh in on that, but I'll say this. The rumours of actors, singers, sports stars who are all apparently in 'Deadpool 3' are fabulous. If all I read was the internet, I would have the greatest cast ever assembled in the history of cinema, so I'll simply say that some of those rumors are true, and some of them aren't."