Rihanna is taking it off for a good cause. The “Diamonds” singer goes topless in her ad for MAC Cosmetics’ Viva Glam campaign, which she revealed on Twitter.

She dons a blonde bob and covers her breasts with her arms in the racy photo, shot by Inez and Vinoodh. All sales from Viva Glam lip products will benefit women, men, and children living with HIV/AIDS.

“#MACgirlz my new #VIVAGLAM lipstick AD CAMPAIGN is out now!” tweeted RiRi. “Every penny you spend on my #VIVAGLAM lipstick goes to the @maccosmetics MAC AIDS Fund to support people directly affected by HIV/AIDS!”

Past Viva Glam spokeswomen include Nicki Minaj, Lady Gaga, Lil’ Kim, Missy Elliott, Eve, Mary J. Blige, Christina Aguilera, and Fergie.

The 25-year-old singer had previously inked a deal with MAC for her own line of cosmetics.