The impressive gown - which was worn by Florence Pugh in the 2019 thriller movie - is part of an array of items being auctioned off by A24 Films to raise money for coronavirus relief efforts, and both Halsey and Ariana are keen to get their hands on the dress.
Ariana, 26, made her plans known on her Instagram Story when she shared a screenshot that showed several of the her friends forwarding her the news that the dress would be going under the hammer.
She wrote alongside the image: ''I was already planning to have it made anyway bye (sic)''
In another post, the '7 Rings' hitmaker told actress Florence directly that she would be bidding on the gown ''as soon as possible''.
She said: ''@FlorencePugh I'm crying
''also I'm bidding as soon as possible. (sic)''
And Halsey, 25, is having to convince herself not to bid on the dress, as she took to Twitter to repeatedly warn herself to stay away from the auction.
She wrote: ''me, to myself: dont bid for the midsommar may queen outfit dont bid for the midsommar may queen outfit don't bid for the midsommar may queen outfit don't bid for the midsommar may queen outfit don't bid for the midsommar ma (sic)''
Other props going under the hammer include the bedazzled Furby from 'Uncut Gems', and the mermaid figure used by Robert Pattinson in 'The Lighthouse'.
The 'Midsommar' props auction begins on Monday (27.04.20), and proceeds will benefit the New York Fire Department's non-profit FDNY Foundation.
Nobody is impressed by Demi "coming to the rescue".
Let's leave gatekeeping in 2020.
These are the albums we're looking forward to most this month.
David Bowie poses difficult questions about lack of racial diversity on MTV.
As Gal Gadot's Wonder Woman 1984 seems to be everywhere at the moment we thought we'd take a look back at the wonder women of music back in 1984.
Taylor Momsen radiates some seriously ethereal beauty in the video for The Pretty Reckless' latest single '25'.
The 2020 pop masterpieces that we've had on repeat.