Apple engineers are “racing” to change the algorithms used for the blood oxygen sensor in the Apple Watch to avoid having to halt device sales, reports Bloomberg. Apple on Monday said that it will stop selling the Apple Watch Series 9 and Apple Watch Ultra 2 in the United States starting on December 21 due to an imminent import ban stemming from a patent dispute with medical device company Masimo.

Sources that spoke to Bloomberg said that engineers are adjusting how oxygen saturation is determined and how the data is provided to customers, updates that will presumably remove technology that is allegedly violating Masimo patents. The work is in line with Apple’s statement that it is “pursuing a range of legal and technical options” to make sure that Apple Watch sales are able to resume as soon as possible.