The filmmaker took to Instagram on Tuesday to post a photo of the script's title page.
Phillips took to Instagram on Tuesday to confirm that his Oscar-winning 2019 film Joker is getting a sequel, penned by himself and Scott Silver -- who also co-wrote the first film.
Phillips shared a pair of snapshots, beginning with a pic of the script's cover page, revealing the sequel is tentatively titled Joker: Folie à Deux.
The second snapshot in the slideshow was an artistic black-and-white candid pic of star Joaquin Phoenix -- who earned his Oscar for playing the title character -- reading the script over while smoking a cigarette.
The first Joker -- which was originally imagined as a standalone drama set in the Batman universe but outside the cannon of the comics or the film adaptations -- was set in the early '80s, and followed the mentally unstable failed clown Arthur Fleck as he spiraled into madness and sparked a violent riot in the city of Gotham.
Not much is known about the plot of Phillips' forthcoming follow-up, outside of the title. Folie à Deux is a term that means a shared delusion or nearly identical mental disorder that presents in two different people.
Whether the title refers to Joker's famously disturbed relationship with Batman or possibly his notoriously unhealthy relationship with love interest Harley Quinn remains to be seen.