Billionaire Bill Gates and left-wing political wunderkind Alexandria Ocasio-Cortez might disagree on how much taxes the rich should pay, but they are on the same page when it comes to robots.

Tax them, too.

Ocasio-Cortez mentioned applying a tax rate of 90% on robots or the companies that use them at weekend festival in Austin, Texas. The first-term New York congresswoman suggested the idea had originally come from Bill Gates, the uber-rich co-founder of Microsoft MSFT, -1.71% .

Gates has promoted a “robot tax” for several years, though he’s never actually suggested a specific rate and probably wouldn’t favor a levy that high.

In an interview with The Verge last month, Gates repeated his view that robots who replace human workers ought to be taxed as if they were real people themselves.

“Right now, the human worker who does, say, $50,000 worth of work in a factory, that income is taxed and you get income tax, social security tax, all those things,” he said. “If a robot comes in to do the same thing, you’d think that we’d tax the robot at a similar level.”

From Gates’ perspective, robots would be so much more productive at their jobs than humans that companies who replace people with machines will still come out ahead even with such a tax. He also contends a robot tax will slow down the replacement of humans with machines and give society more time to adjust.

The European parliament considered a tax on robots in 2017, but it rejected the proposal on worries that it would slow innovation and put the continent at an economic disadvantage. The U.S. has not seriously considered such a tax.

Critics of a robotics tax point out that the side-effects of technological change on labor markets have been overstated, often wildly so, since the early 1800s.

Consider the modern U.S. The economy has added almost 21 million jobs in the past eight years and the unemployment rate has fallen to a 50-year low even as the speed of automation accelerated.

Read: The rise of the robots and decline of inflation: How AI is keeping prices low

Ocasio-Cortez, for her part, said she welcomed a future in which robots replaced people and freed humans up for more leisure time.

“We should not feel nervous about the toll booth collector not having to collect tolls anymore,” she said at the South by Southwest Conference & Festival in Austin. “We should be excited by that.”

The bigger problem, she argued, is that businesses don’t pay workers the amount of money equal to how much profit they generate by their labor.

“We should be working the least amount we’ve ever worked, if we were actually paid based on how much wealth we were producing,” she said. “But we’re not. We’re paid on how little we’re desperate enough to accept. And then the rest is skimmed off and given to a billionaire.”

Billionaires like Gates. Ocasio-Cortez has floated a proposal to raise the top marginal tax on ultra-rich people to 70% from the current rate of 37%.

While Gates said the rich should pay more, he called a 70% rate “extreme” and said the wealthy would find ways to avoid it.