If you have an Apple eBook credit coming from Amazon’s online book store, you have four days to cash in.
A year ago, when the U.S. Supreme Court refused to hear its appeal of a class action suit, Apple (AAPL) was ordered to offer $400 million in refunds to people who bought specified e-books between April 1, 2010 and May 21, 2012.
The aggregate refund of $400 million was issued via credits to people who bought books via Amazon, Barnes & Noble, Kobo, and Apple’s iTunes.
The deadline to cash in on the credit from Amazon is June 24, 2017 at 11:59 p.m. PT.
Book buyers should have been notified about their credits via email. To check on whether are due some money, log into your Amazon (AMZN) account and check this page to see if they have credit coming.
Get Data Sheet, Fortune’s technology newsletter.
If you care about the nitty-gritty, attorneys general from 33 states plus other plaintiffs claimed Apple and five publishers—Hachette, HarperCollins, MacMillan, Penguin, and Simon & Schuster—conspired to fix and inflate the retail prices of e-books, according to a website outlining the lawsuit and settlement,