Taylor Swift has put her music back on Spotify, on the same day Katy Perry's new album comes out.
The two stars are in a long-running feud which reportedly started as a disagreement over backing dancers.
Taylor pulled her songs from Spotify back in 2014, after criticising the effect streaming services were having on the music industry.
She says her return is a "thank you" to fans, in honour of her last album 1989 selling 10 million copies.
There have been rumours of a rift between Taylor Swift and Katy Perry for years, but it wasn't until last month that either publically admitted it.
"There's a situation," Katy Perry told US TV host James Corden. "She started it and it's time for her to finish it."
It's thought the Taylor Swift song Bad Blood and the Katy Perry track Swish Swish, are both about the feud.
And, by the looks of this latest move from Taylor, it's far from over.
Katy Perry started live streaming her new album, Witness, on Thursday night. She also announced new tour dates, some of them in the UK.
Taylor Swift's music appeared back on Spotify at midnight - exactly the same time Witness was released - after almost three years away from the service.
"In celebration of 1989 selling over 10 million albums worldwide and the RIAA's 100 million song certification announcement, Taylor wants to thank her fans by making her entire back catalogue available to all streaming services tonight at midnight," the post on Instagram read.
A Spotify spokesperson said: "We can confirm that Taylor Swift's entire back catalogue is now available on Spotify for her millions of fans to enjoy".
She's also now on Amazon Music.
"We love Taylor and we're happy to have 1989 now on Amazon Music for all fans to stream and enjoy," said the firm's vice-president Steve Boom.
She had limited her tracks to Spotify's rival, Apple Music, after convincing it to pay artists more.
"We don't ask you for free iPhones. Please don't ask us to provide you with our music for no compensation," she wrote in an open letter in 2015.