CHICAGO (CBS) — Some parents in Waukesha, Wisconsin are a little miffed after their kids’ school decided they can’t wear Halloween costumes for the annual fall festival.

Parents at Hillcrest Elementary School said, for years, they have watched their kids parade around the gym in costume for the fall festival, but this year the school isn’t allowing costumes.

“The reasons were the most frustrating to me,” Dawn Pelej told CBS 58 in Milwaukee.

Pelej said the principal explained some kids don’t celebrate Halloween, and others’ parents might not be able to afford costumes.

“I think we missed an opportunity for our kids to practice kindness. I know my son would have happily donated costumes that he’s worn in the past, or gone to Target with me and picked up a few costumes to donate to the school,” Pelej said.

Instead of the costume parade, the school is having a “Hat Day” to raise money for hurricane victims. Instead of costumes, kids can wear any hat they want, as long as it’s appropriate.