Tariffs could add $900 million to Apple’s costs in the quarter ending in June, CEO Tim Cook said during the company’s earnings call yesterday.

Apple reported a Q2 earnings per share and revenue beat as well as better-than-expected iPhone sales, but the stock fell, likely due to weakness in sales in China and supply chain uncertainty thanks to tariffs, which are pushing the iPhone maker to move production out of China. The big asterisk is that the $900 million number assumes “current global tariff rates, policies and applications do not change” for the remainder of the quarter — a big if.

With that $900 million hit to its cost of goods sold in mind, Apple expects a gross margin between 45.5% and 46.5% next quarter, on revenue that it expects to grow “low- to mid-single digits year-over-year.”