WhatsApp is raising its minimum age for European users from 13 to 16.
It comes ahead of the roll out of the EU's new data protection rules, General Data Protection Regulation (GDPR), which come into effect next month.
The Facebook-owned messaging service will ask people to confirm how old they are when new terms are rolled out in the coming weeks.
It's unclear how this will be checked.
According to WhatsApp, the minimum age will remain 13 outside Europe.
In a blog post explaining the changes, the company said: "WhatsApp has established an entity within the European Union to provide your services there and to meet the new high standards of transparency for how we protect the privacy of our users.
"We are not currently sharing account information to improve your product and ads experience on Facebook."
It adds that it wants to 'work closer' with other Facebook companies in the future, saying it will provide updates as necessary.