“As soon as he said yes, it was like a family member giving you that love and support that I needed,” Krasinski said of his reunion with Carell on the Paramount film.

Steve Carell, John Krasinski, Cailey Fleming and Ryan Reynolds attend Paramount's "If" New York premiere

John Krasinski planned a large portion of his new movie IF around longtime friend Steve Carell — before he had spoken to his former The Office co-star about the role.

At IF‘s New York premiere on Monday, Krasinski gestured to wife Emily Blunt — who has a voice role in the new film — and revealed, “The last time I wrote a part for someone was for her in A Quiet Place and I was too nervous to tell her about it, and the same thing happened with Steve.”

“I was writing [animated character] Blue to be Steve because of his sense of humor and how sweet he is, and how incredibly vulnerable and also how big and open-hearted he is and he gives great hugs,” he continued. “So I was like, ‘If he doesn’t do this, we’re in trouble.’ And as soon as he said yes, it was like a family member giving you that love and support that I needed. As soon as he jumped on, I knew we were off to the races.”

IF follows a young girl (Cailey Fleming) who discovers she can see everyone’s imaginary friends, and goes on an adventure to reconnect forgotten IFs with their kids. Carrell voices big purple monster Blue, among a voice cast that also includes Bradley Cooper, Awkwafina, Matt Damon, Amy Schumer and Maya Rudolph.

Krasinski — who wrote, directed and co-stars in the film — said he bounced a lot of ideas off his and Blunt’s kids in the process, explaining, “I pitched them the idea of the script, I showed them all the drawings I did while I was writing the script — I’m a terrible artist, so I had to walk them through that. They told me what was cute about certain IFs, what wasn’t cute, what they wanted to change.”

He also revealed his daughters’ imaginary friends are in the movie: “Ally the pink alligator is one of my daughter’s and the other one is the flaming marshmallow, so it’s a family affair. And my wife’s the unicorn so come on, we’re all involved.”

Ryan Reynolds, who stars alongside Fleming, said he found “John’s take on this film to be super inspiring,” while also taking inspiration from Gene Wilder and from his own kids.

“They have just a constant and kind of ceaseless sense of play and I love that, and I watch them and I find myself kind of doing impressions of my kids,” Reynolds told THR. “Shawn Levy, who directs Deadpool & Wolverine, he called it about halfway through shooting that movie — I was writing the script in the voice of my 4-year-old daughter Betty at many times, just in the cadence of how she speaks. So I find I really absorb a lot of their vibes and translate them through whatever my adult idiocy would be.”