Popular messaging service WhatsApp is banning under-16s from using its platform in the European Union.
Users must currently be at least 13, but the firm is changing the rules ahead of the introduction of new EU data privacy regulations in May.
The app, which is owned by Facebook, will ask users to confirm their age when prompted to agree new terms of service in the next few weeks.
It has not said how the age limit will be enforced.
At present, WhatsApp does not ask users their age when they join, nor does it cross-reference their Facebook or Instagram accounts to find out.
About a third of all UK-based 12- to 15-year-olds active on social media use WhatsApp, according to a 2017 report by the media regulator Ofcom.
That made it the fifth most popular social network with the age group after Facebook, Snapchat, Instagram and YouTube.
The EU’s General Data Protection Regulation (GDPR), which comes into force on 25 May, will give people much more control over how companies use their information.
It also includes specific rules to protect youngsters whose personal data is processed in order to provide them with online services.
Such websites and apps are obliged to “make reasonable efforts to verify” that a parent or guardian has given consent for their child’s data to be handled.
The law says this obligation applies to under-16s, although some countries – including the UK – have been allowed to set the cut-off limit lower, at 13.