Frankie Muniz reveals the bizarre reason he ended Hilary Duff friendship

He’s coming clean.

Frankie Muniz admitted he ended his friendship with Hilary Duff after working on the 2003 film “Agent Cody Banks” because he was not a fan of his co-star’s mom.

“Hilary Duff was probably one of my first friends when I moved to LA to film ‘Malcolm [in the Middle],’” Muniz recalled on the Sept. 2 episode of “The Joe Vulpis Podcast.”

The pair were introduced through mutual friends in Los Angeles as several of the “Malcolm in the Middle” star’s pals lived in an apartment complex in Burbank, Calif., that was known to house numerous child actors.

“We became really, really good friends. We had a really great relationship for a long time,” he continued.

After becoming close, Duff, 38, asked for Muniz, 39, to make an appearance on her Disney show “Lizzie McGuire” playing himself in 2002.

“I was on the set of ‘Lizzie McGuire,’ and I was in Hilary’s dressing room and her mom was there,” Muniz remembered, describing Duff’s mom, Susan, as “the epitome of a stage mom.”

“She was intense. Hilary was so cool, we had an awesome relationship, but her mom was super intense. And my mom was the opposite,” he added.

The “Big Fat Liar” star went on to explain that his mom would often “hide” while he worked on set because she “didn’t want to be in the way.”

While working with Duff on her show, Muniz — who was in his teens at the time — remembered the Disney star’s mom asking him, “What are you doing this summer?’”

“And I go, ‘Oh, I’m filming this movie where I’m playing like a junior James Bond. It’s called ‘Agent Cody Banks,’” he answered back.

At which point, he claims Susan asked Muniz if there was “a girl” role in the movie that might be good for Duff to take on. But, Muniz gave a noncommittal response to the probe.

On the podcast, Muniz explained that he believed the role on Natalie Connors, which ultimately went to Duff, was going to be played by “Smallville” star Kristin Kreuk, whom executives had previously expressed an interest in.

“The next morning, I show up to the set. I go into her dressing room to hang out. And her mom’s like, ‘Guess what? We’re going to be spending the summer together.’” Muniz shared.

Showing his confusion, Muniz excitedly asked Duff’s mom if she would be filming a different film in Vancouver, Canada, where the 2003 flick was shot.

But Susan told him, “No, she’s doing ‘Cody Banks’ with you… They signed the contract last night.’ ”

“The movie you knew nothing about yesterday?” Muniz remembered asking in disbelief.

He went on to share that the casting took place after “calls were made” and because executives knew of his friendship with Duff, they “assumed it was fine” despite Muniz’s stipulations in his contract that gave him a say in the casting of his love interest.

“Needless to say, I wasn’t thrilled about it. And not because I didn’t want it to be Hilary,” he said.

“I don’t know how much I want to say. I’m trying to think about it because I’ve already said way too much,” Muniz said of the ordeal, adding that he had an “amazing time” filming the movie, but was “very sad when Hilary’s mom would come on set.”

“And if I told you I’ve never talked to Hilary since the last day of filming. I’ve not said one word to her since then. So that’s the truth of that,” he closed.  

“I regret not just continuing to be friends with her because we had a great friendship for such a long time, and her mom… it pissed me off,” he shared.

Though, Muniz added that he would “love to catch up” with Duff now that they’re both far past the drama of the film. “I would love to even talk about that because I’m sure she doesn’t know any of that happened.”

Duff’s reps did not immediately respond to Page Six’s request for comment.