The screens on some Apple Watch models may crack and Apple is offering free fixes for affected gadgets.

“Under very rare circumstances, a crack may form along the rounded edge of the screen in aluminum models of an Apple Watch Series 2 or Series 3,” the company said in a statement.

Apple or an Apple authorized service provider will replace the screen on eligible units that exhibit this type of crack, free of charge, the company also said.

After a slow start in 2015, the Apple Watch is finally generating significant revenue to the company. But it is also facing tariffs from the Trump administration starting Sunday as part of a trade war with China.