Bob Newhart Predicted Elf Would Be a Holiday Classic Early on: 'Will [Ferrell] Had Such Charm'

Since 2003, Elf has been a holiday mainstay due to its pure Christmas spirit and hilariously quotable lines — and above all, according to Bob Newhart, thanks to his costar Will Ferrell.

Speaking to PEOPLE, the comedy legend, 90, recalls predicting that the movie would be a smash hit the first time he laid eyes on David Berenbaum’s script.

“They sent me a script. I knew Will was doing it and I think I knew Ed Asner was in it,” Newhart says. “I read the script and I said to [his wife] Ginnie, ‘This is going to be a perennial. This is going to be like Miracle on 34th Street. They’re going to be showing this every Christmas, I guarantee.'”

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According to Newhart, Ferrell and director Jon Favreau “weren’t given [enough] credit.”

“It could have been a terrible movie. It could have been just a stupid person who thinks they’re still an elf,” he says. “But Will had such charm and Jon Favreau shot it in such a way that people just love it. They just love it!”

Plus, Newhart adds, he earned a whole new group of (much younger) fans.

“I got a lot more mail in crayon,” he jokes.

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In an interview with Rotten Tomatoes last year, Ferrell, 52, and Favreau, 53, looked back fondly on the film, which was filmed in New York City and released just a few years after 9/11.

“It was a really challenging time and it was nice to bring a nice breath of innocence to the world, and especially to the city, at that time,” Ferrell said. “I’m really proud of it. If it’s ever in a theater or playing on television, I love to check in on it. And I can tell through social media that it’s something that people have made a tradition of … and that really makes me happy. It’s the best part of the job.”