Snapchat users were warned this week to beware of messages sent from unknown users saying you’ve won a prize.

According to the Better Business Bureau, scammers have figured out a way to misuse Snapchat, a popular photo and video sharing mobile-phone application.

The scammers send users a photo saying they have won a prize and then give instructions to go to a website. The BBB said the websites instruct users to choose from a list of smartphone apps and download one.

“This could just be a unscrupulous way to generate app downloads,” said the BBB, also warning that the apps could contain malware.

Snapchat users are advised to change their settings to only receive snaps from approved friends.