Microsoft Corp. co-founder Bill Gates on Wednesday became the latest billionaire to criticize Elizabeth Warren for her signature wealth tax.

In an appearance at the New York Times DealBook Conference, Gates said he’s paid $10 billion in taxes and wouldn’t have minded paying twice that, but joked that, “When you say I should pay $100 billion then I’m starting to do a little math about what I have left over.”

Gates supports higher estate taxes and “super progressive tax systems,” but questioned whether Warren’s 6% tax on assets of the wealthy would prove counterproductive. “I do think if you tax too much, you do risk the capital formation’’ and innovation, as well as imperiling the U.S. “as the desirable place to do innovative companies,” he said.

He said he hasn’t spoken to Warren about her tax plans. “I’m not sure how open-minded she is,” he said, or that she’d want to talk to “somebody who has large amounts of money.” Warren’s tax would apply to households worth $50 million or more and would pay for a bevy of progressive proposals including her $21 trillion Medicare For All plan.

Two other billionaires, JP Morgan Chase & Co. Chief Executive Officer Jamie Dimon and investor Leon Cooperman, have criticized Warren’s wealth tax. She responded to both via Twitter, saying they should be willing to pay more in taxes to help others achieve the American Dream.

This article was provided by Bloomberg News.