Apple has been ordered to pay an additional $184 million in interest following a patent infringement case brought by Masimo. The payment comes on top of the $634 million in damages previously awarded by a jury.

The original verdict was delivered in November last year, when a jury found that Apple had infringed Masimo’s patents relating to heart rate monitoring technology used in Apple Watch models. Masimo was awarded $634 million in damages.

Judge James Selna has now rejected Apple’s argument that adding interest would provide Masimo with an unfair windfall. The judge cited US Supreme Court guidance stating that interest covering the period when royalty payments would have been received is intended to make the patent owner whole.

However, the judge also rejected Masimo’s request for a 7% interest rate, which would have increased the interest payment to $243 million. Instead, the court used Masimo’s own borrowing rate, compounded annually from the beginning of the infringement period.

As a result, Apple’s total bill has increased from $634 million to approximately $818 million. While the amount is relatively small compared with Apple’s overall finances, the ruling represents a significant additional award for Masimo.