A former worker for Apple and Infosys whose lawsuit against the companies over alleged visa fraud was thrown out last month has filed a notice of appeal.

Carl Krawitt alleged in his lawsuit that the two firms conspired to bring in Indian tech workers on a B-1 visa for a six-week training program at Apple when the law required the harder-to-get H-1B visa. Apple and Infosys argued that their use of the B-1 visa was legal and appropriate. Krawitt, under a legal process for whistleblowers, was making the case on behalf of the federal government.

Apple and Infosys did not respond to requests for comment.

In March, a federal court judge in San Jose threw out the case, after earlier dismissing it but leaving a path open for Krawitt to submit an amended complaint, which he did. In her March ruling, Judge Lucy Koh terminated the case “with prejudice,” meaning Krawitt could not bring it again. But in an amended order, Koh left open the ability of the federal government to pursue the case on its own.

The H-1B, intended for jobs requiring specialized skills and awarded through a lottery, has become a flashpoint in America’s immigration debate. Major Silicon Valley tech companies lobby for an increase to the annual 85,000 cap on new visas, arguing they need more visas to secure the world’s top talent. Critics point to reported abuses by outsourcing companies, and contend that large tech firms use the H-1B to acquire cheaper foreign labor via outsourcers.

Krawitt filed a notice of appeal Wednesday in U.S. District Court in San Jose and plans to argue Koh erred in dismissing the case. According to the court schedule, he is to file an opening brief — outlining the reasons he and his legal team believe Koh erred in her ruling and why an appeal is justified — on July 19. Apple and Infosys are to provide their responses a month later.