Metallica played a virtual concert to kick off this year’s online edition of BlizzCon, Blizzard Entertainment’s annual gaming convention. But midway through the free livestream, the Tech Times reports, Twitch replaced Metallica’s audio with generic, twinkly royalty-free background music to avoid a DMCA takedown. (The performance was preceded by an ominous chyron reading, “The upcoming musical performance is subject to copyright protection by the applicable copyright holder.”)

Notably, it was only the livestream on the front page of Twitch Gaming that was affected; the streams on Blizzard’s official YouTube, website, and Twitch page reportedly continued without any issues. Twitch has faced thousands of DMCA takedowns from major record labels over the past year, and the streaming platform has warned streamers not to play any recorded music.

Many online commentators have pointed out the irony of this happening to Metallica, as the band’s lawsuit against Napster in the early 2000s paved the way for exactly these kinds of copyright issues. Watch the swapped-audio Twitch Gaming livestream (Metallica shows up at 1:11:15) and the unedited version of “For Whom The Bell Tolls” below.