Berkshire Hathaway (BRK-A, BRK-B) CEO Warren Buffett, whose company is the largest stakeholder in Apple (AAPL), says he lacks the iPhone skills of a toddler despite a personal tutorial from the smartphone maker’s CEO Tim Cook.

“I went out to California, and Tim Cook very patiently spent hours trying to move me up to the level of the average two-year-old,” Buffett told Yahoo Finance’s editor-in-chief Andy Serwer in an exclusive interview on March 10 in Omaha, Nebraska. “And didn’t quite make it.”

But Buffett doesn’t hold it against Cook or his top-selling smartphone.

“We had a lot of fun. He is a terrific guy,” Buffett said. “Unbelievable product.”

Berkshire Hathaway’s position in Apple was worth $73.7 billion as of Q4 2019, which is more than double the cost of the investment. Berkshire first invested in Apple in 2016.

Read more: Warren Buffett: Lessons from a legendary investor

Last May, Apple released an iPhone game based on the Oracle of Omaha called “Warren Buffett's Paper Wizard," which alludes to Buffett’s childhood job as a paper boy and the newspaper toss competition held at Berkshire Hathaway’s annual shareholder meeting.

Buffett said he never uses apps, and even sometimes struggles to make phone calls on the device.

“Yesterday, I was someplace,” he said. “Somehow I was having a little trouble just getting into — but this is only me, any two-year-old could do this — but I was having a little trouble getting to the part where I actually phone somebody.”

Buffett made the comments during a conversation that aired in an episode of Yahoo Finance’s “Influencers with Andy Serwer,” a weekly interview series with leaders in business, politics, and entertainment.

Since 1965, Buffett has run Berkshire Hathaway, which wholly owns over 60 companies, including Geico and Dairy Queen, and holds minority stakes in Apple (AAPL) and Coca-Cola (KO), among others. He has a net worth of $82.5 billion and has vowed to give away nearly all of it as part of The Giving Pledge.

Buffett did not bring his iPhone to the interview with Serwer.

“I would be afraid it would ring, and I wouldn’t know what to do with it,” Buffett says.

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