Marie Osmond took to the Las Vegas Strip on Thursday to protest against hidden charges in Sin City hotels.

The singer was joined by 50 showgirls, as well as magicians Penn & Teller, to speak out against mandatory resort fees, which can be as much as $24.99 per night.

The charges, which cover amenities such as internet service and gym access, are often not included in advertised room rates, but Osmond insists travelers should be told about the costs at the time of booking.

She says, "It's extremely important for visitors to the city to be aware of the high prices they could be paying in mandatory resort fees. I am proud to be part of this key initiative."

The star and her brother Donny are currently performing a residency at the Flamingo Las Vegas, which does not charge resort fees.