The dollar first rose after Donald Trump’s election win thanks in part to an idea the president-elect would increase infrastructure spending. But on Tuesday, the U.S. Dollar Index slid 1.2% to 100.35 and hit a low it hasn’t since early December. The index measures the greenback relative to a basket of six other major world currencies.

The dip comes after Trump told the Wall Street Journal on Monday that the U.S. dollar was “too strong.” Trump, revisiting a well-worn argument, said that the strong dollar came in part due to China holding its currency, the yuan, down.

“Our companies can’t compete with them now because our currency is too strong. And it’s killing us,” he told the Journal.

A stronger dollar has the potential to hurt U.S. companies that sell products abroad by making their goods more expensive, according to the Journal.

Still, the dollar is still stronger than it was prior to Trump’s election win. The currency has risen 2.2% since Nov. 8.

Trump’s not the only one who’s warned about the surging dollar. Most recently, private equity giant Carlyle Group’s David Rubenstein called the strong dollar the greatest risk to the economy this year on a World Economic Forum panel. He noted that a more expensive dollar could make it difficult for foreign companies to pay back their debt purchased in the currency.