Several British celebrities who promote products online agreed to disclose upfront if they are being paid to advertise on their social media posts. According to The Competition and Markets Authority, singers including Ellie Goulding and models such as Rosie Huntington-Whiteley and Alexa Chung will clearly state if they are being paid or have received gifts for products they promote online.

The CMA wrote to a variety of celebs in August, asking about their posts and what business agreements they have with these brands. In addition, it sent a number of warning letters, advising celebrities to “review their practices.”

“The enforcement action taken by the CMA has seen a number of social media stars pledge to be more transparent when posting,” CMA Chief Executive Officer Andrea Coscelli said in a statement. “It also sends a clear message to all influencers, brands and businesses that they must be open and clear with their followers.”

Bloomberg notes that consumer protection laws require influencers to clearly state when they are paid or rewarded for promoting, reviewing, or even just talking about a product in social-media feeds. If you fail to label these posts accordingly, it can trick followers into believing that an endorsement is a star’s own, trusted view of a product, the CMA said.