President Trump offered a tip to the world’s largest tech company Saturday – telling Apple it should start building more factories here at home to avoid suffering from a possible tariff hike.

“Apple prices may increase because of the massive Tariffs we may be imposing on China,” he said in an 11:45 a.m. tweet, while he was traveling in the presidential motorcade.

“But there is an easy solution where there would be ZERO tax, and indeed a tax incentive. Make your products in the United States instead of China. Start building new plants now,” Trump recommended. “Exciting!”

The tweet came after Apple warned that Trump’s proposed tariffs on $200 billion of Chinese-made products would affect the company.

The $1 trillion tech giant issued a letter Friday saying that the levies could increase consumer prices of products like the Apple Watch and Mac Mini.