Paul McCartney is suing Sony in an effort to reclaim the copyright of The Beatles catalog that he lost in a sale to Michael Jackson.

Sony/ATV completed purchase of this cache of legendary tunes last year, just before McCartney became eligible to reassert partial ownership again based on a provision of the U.S. Copyright Act of 1976. Since then, Sony/ATV has apparently ignored McCartney’s requests to discuss a future transfer.

“Paul McCartney has today filed a lawsuit in federal court in New York against Sony/ATV to confirm his ownership in his U.S. reversionary copyrights – which are granted to him by U.S. copyright law – in the songs he wrote with John Lennon and recorded with the Beatles,” a McCartney spokesperson said.

According to the Copyright Act, tracks written before 1978 – which include all of the Beatles’ output – revert back to the composers after 56 years. His earliest work with Lennon would become available in 2018, then continue reverting yearly through the anniversary of the Beatles’ dissolution in 2025.