Shein and Temu rapidly expanded in the U.S. using the de minimis provision to deliver ultra-cheap fast-fashion items from China.

Trump signed an executive order Wednesday to end the so-called “de minimis” exemption on merchandise from China and Hong Kong. The rule allowed companies to avoid import taxes and certain customs paperwork on packages worth $800 or less.

The administration is shutting down the “de minimis” loophole, which could affect businesses ranging from Etsy sellers to e-commerce behemoths.