Snapchat said on Thursday it would alter its app to make it harder for malicious users to collect and leak millions of usernames connected to phone numbers. The move comes after a group calling itself SnapchatDB rang in the New Year by leaking 4.6 million partially redacted phone numbers, in a stunt they said was designed to raise awareness about security flaws in Snapchat’s app. The leak was made possible by the app’s Find Friends feature, which lets users find any friend who has shared a phone number with the service. SnapchatDB used the feature to upload a huge volume of phone numbers to the service to discover Snapchat accounts linked to them, and created a searchable database of the results. “We will be releasing an updated version of the Snapchat application that will allow Snapchatters to opt out of appearing in Find Friends after they have verified their phone number,” Snapchat said in its blog post.