Paul McCartney is fighting to get his Beatles songs back.

The musician filed a lawsuit against Sony/ATV Music Publishing on Wednesday in a attempt to regain the rights to a number of Beatles songs that he wrote or co-wrote with former band member, John Lennon, CNN reports. The lawsuit is the latest development in McCartney’s pursuit of the rights.

McCartney is suing for the rights to songs such as “Yesterday,” and “I Want to Hold Your Hand,” among others, according to court documents obtained by CNN.

Sony and entertainer Michael Jackson formed Sony/ATV in 1995, about a decade after the late pop star paid $41.5 million to acquire the ATV catalog, which included many Beatles songs. But in March of 2016, Sony took full control of Sony/ATV after Jackson’s estate agreed to sell its 50% stake for $750 million.

Though Sony still owns the rights, McCartney is arguing that the 1976 Copyright Act should allow him to reclaim ownership, CNN reports. The law gives songwriters the ability to reclaim ownership after a certain period of time: For songs written before 1978, they can do so after 56 years; for those written on or after 1978, the deadline goes down to 35 years.

“Sony/ATV has the highest respect for Sir Paul McCartney with whom we have enjoyed a long and mutually rewarding relationship with respect to the treasured Lennon & McCartney song catalog. We have collaborated closely with both Sir Paul and the late John Lennon’s Estate for decades to protect, preserve and promote the catalog’s long-term value,” a Sony/ATV Music Publishing spokesperson told Fortune in a prepared statement. “We are disappointed that they have filed this lawsuit which we believe is both unnecessary and premature.”