Twitter CEO Jack Dorsey lost 200,000 followers on his own social network after a purge of fake followers.

Twitter has been deleting so-called “locked accounts” as part of an initiative to cleanse the platform of bots. These are profiles that Twitter locks if they exhibit suspicious behavior like tweeting a large amount of unsolicited replies or mentioning users en masse.

The development follows a campaign by Unilever to crack down on the spread of fake followers. The consumer goods giant said last month it would no longer work with internet “influencers” who purchase followers to artificially inflate their social media following.

Fake followers are a particular headache for the advertising industry. They can deceive marketers about the traction and success of an ad campaign. The phenomenon also means that advertisers spend unnecessarily to reach digital audiences that don’t exist.

Twitter began removing locked accounts on Thursday, to boost “accuracy and transparency” on the platform.

After the purge began, Dorsey said in a tweet: “I lost 200k followers.”

Tweet

According to social media analytics site SocialBlade, Dorsey lost 226,354 followers on Thursday.

Dorsey is not the only celebrity losing followers.

President Donald Trump lost more than 300,000 followers while former President Barack Obama lost more than 2.3 million followers.

Pop stars Katy Perry and Justin Bieber lost around 2.8 million and 2.7 million, respectively.

And Twitter’s own account lost the biggest amount, with its follower count down by more than 7.7 million.

As for the average Twitter account, the social network said most users shouldn’t see a big change, and should expect to lose around “four followers or fewer.”