Yesterday, YouTube announced a platform-wide purge of spam subscribers, tweeting that creators “may see a noticeable decrease in your sub count” as a result. Affected creators will receive an alert in their YouTube Studio dashboards, the company said.

In a Product Forums post, YouTube explained that it regularly verifies subscriber legitimacy, and has “recently identified and fixed an issue that caused some spam not to be removed.” While the company clamps down on purchased subscribers to ensure the community’s authenticity, the move is bound to frustrate non-offending creators whose numbers are dashed as a result (because spam subscribers purchased by one creator typically subscribe to other channels, too, in order to avoid detection).

Comparable purges in the past have caused quite a stir.

Heads up, Creators: On Dec 13-14 you may see a noticeable decrease in your sub count as we remove spam subscriptions. If spam is removed, you’ll see a YouTube Studio alert: https://t.co/3KWMixSXRl This should help give you confidence that the subs you do have are real fans! — Team YouTube (@TeamYouTube) December 13, 2018

YouTube said that it does not expect the purge to impact watch-time, though creators who fall below the 1,000-subscriber minimum to be considered for the YouTube Partner Program will lose their standing, and need to reapply.

In its most recent quarterly YouTube Community Guidelines Enforcement report, YouTube said that it deleted 1.7 million channels and 50.2 million videos in the third quarter — 80% of which were deemed to be spam. The rest of the removals were due to nudity or sexual content, and for child safety concerns, the company said.