University of Michigan economics professor Justin Wolfers has trashed Donald Trump’s claim that grocery prices are down.

The president told Fox News’ Laura Ingraham in an interview that aired on Monday that the United States is “doing phenomenally well” under his leadership and currently enjoys the “greatest economy we’ve ever had,” with just beef and coffee prices too high.

“Look, every word the president just said is a lie,” Wolfers told CNN’s Kaitlan Collins on Tuesday. “Worse with that, it’s such a lie that I worry that there’s literally a break with reality inside the man’s mind. I can tell you that because I’m a statistics nerd, and you can go to the Bureau of Labor Statistics, they’ve got people in supermarkets all across the country, and almost every category of goods or services sees the prices rising.”

Wolfers acknowledged there’s a “reasonable argument to be had” about whether inflation is too high or too low.

But the fact remains that there is most definitely inflation, he said.

“And it’s not just the nerds at the BLS who see it,” the economist pointed out. “When companies are giving their earnings reports, they’re telling us they’re raising their prices. Every single viewer on the other side of this television set knows exactly what’s happening, which is prices are rising.”

He added, “I don’t understand the logic of looking us in the eye and telling us an outright falsehood.”

Earlier on MSNBC, Wolfers said Trump’s claim that prices are down under him was “quite literally false.”

“There’s not a single way you can interpret a word that the man’s saying right now as being remotely reflective of either what we’re seeing in data from all across the country,” he said, “or in people’s everyday lives.”