Twitter is preparing to purge old, inactive accounts unless users log in to them soon, according to Elon Musk.

Musk tweeted a warning to users with old, inactive accounts, saying the company will begin purging them.

It’s still not clear what constitutes an “inactive”” account. Twitter’s official policy says the label applies to any account that has not been accessed in 30 days, although the cutoff limit was six months as recently as April, according to Ars Technica. Whether that still applies, or Musk has a different definition in mind, remains to be seen.