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UPDATE: The morning after releasing his surprise album, Untitled Unmastered, Kendrick Lamar clarified the tracks on Twitter. “Demos from To Pimp A Butterfly. In Raw Form. Unfinished. Untitled. Unmastered,” he tweeted with a link to collection.

EARLIER: Rapper Kendrick Lamar has released a new album, Untitled Unmastered.

The project, which Lamar announced on Twitter, features eight tracks, presumably of material the Grammy-winning rapper created while working on his 2015 album, To Pimp a Butterfly. Each song title consists of the word “untitled” and a date between 2013 and 2016. (See the full track list below.)

Lamar has performed several untitled, unreleased songs on late night shows, including on The Colbert Report and The Tonight Show Starring Jimmy Fallon, and he said last month he had a “chamber” of unreleased material that didn’t make it onto his sophomore album: “I think probably close to 10 songs that I’m in love with that I’ll still play and still perform that didn’t make the cut,” he explained.

Fans of the rapper had been hoping for a surprise album after Anthony Tiffith — the CEO of Lamar’s label Top Dawg Entertainment — promised to release a new project this week. Earlier Thursday, album art and a track list for Untitled Unmastered popped up on Spotify. And later, Tiffith confirmed on Instagram that the album would be released Thursday night.

Lamar has had a big year so far, earning five Grammy Awards at last month’s ceremony, including Best Rap Album for To Pimp a Butterfly, and stunning viewers with his performance of “The Blacker The Berry” and “Alright.”

Untitled Unmastered is available now on Apple Music, iTunes, Spotify, and Tidal. See the full track list below.

1. “untitled 01 08.19.2014.”

2. “untitled 02 06.23.2014.”

3. “untitled 03 05.28.2013.”

4. “untitled 04 08.14.2014.”

5. “untitled 05 09.21.2014.”

6. “untitled 06 06.30.2014.”

7. “untitled 07 2014-2016”

8. “untitled 08 09.06.2014.”