YouTube will be paying out millions of dollars in previously unclaimed non-performance royalties to publishers and songwriters, starting in 2017. The National Music Publishers’ Association negotiated an agreement with the Google-owned company over musical works used in videos on YouTube where ownership was previously unknown.

The pact’s intention is to get publishers and songwriters paid for works viewed on YouTube in the past where ownership was previously unknown, and to be paid in the future for those uses. Music publishers will have the ability to opt into the agreement between 12/12 and 2/28.

“It is essential that we work with digital services like YouTube—the most popular digital platform for music discovery—to fix the challenge of incomplete ownership information to ensure royalties are no longer unmatched and music owners are paid accurately by the platforms that rely on their work,” said NMPA President and CEO David Israelite.

Beginning next year, YouTube will provide participating publishers with a list of songs YouTube may have been unable to obtain proper ownership information for. Publishers will be able to claim ownership in those songs and receive accrued royalties from 8/1/12 through 12/31/15.

Any accrued royalties that remain unclaimed will be distributed to participating publishers based on each publisher’s market share and on revenue paid for known usage on YouTube during the initial accrual period. The agreement, however, will not affect the rights of any publisher or songwriter who does not choose to participate.

Tamara Hrivnak, Head of Music Partnerships, Americas, for YouTube and Google Play, noted “we’re committed to making sure that publishers are paid for the usage of their works on our platform.”