In yet another chapter of Cannes’ dress code kerfuffle, a new petition launched by citizen activist social network Care2 asks the Cannes Film Festival to clarify rules over red carpet screenings’ required attire.

Care2, which deems the festival’s black-tie dress code “sexist,” specificially demands that the festival state its requirement regarding high heels for women. The petition has already been signed by almost 2,700 people.

The controversy comes after Cannes security officials repeatedly turned away women wearing flat shoes.

The fest’s director Thierry Fremaux raised the issue Thursday at the Women in Motion talk organized by fest sponsor Kering.

“Nobody is obligated to wear heels on the red carpet,” Fremaux said. “One of our agents screwed up, and we apologized right away.”

Compared with other top festivals like Berlin, Venice and Toronto, Cannes has the most demanding rules regarding red carpet attire, even for men, who must wear tuxedos and bow ties. There have even been cases of men being turned away for wearing brown shoes instead of black.

But many say that standards such as the formal dress code give Cannes a cachet and glamour unmatched by other festivals.