“Circumventing or blocking advertisements in the Spotify Service, or creating or distributing tools designed to block advertisements in the Spotify Service,” is prohibited, the user guidelines read. Spotify also notes that breaking that rule or any other guideline “may result in immediate termination or suspension of your Spotify account.” This change was also detailed in an email to Spotify users, according to TechCrunch.

Ad blockers have been a long-standing problem for Spotify, especially as it doubles down on its efforts to grow its paid tier. Users can listen to Spotify for free with some limitations, especially on mobile, for free with intermittent ads. The paid service opens up all options and removes all advertisements. Spotify has been giving its free users more elements of its paid level by allowing certain playlists to play on demand on mobile or allowing users to disable ads for an hour after listening to one longer advertisement. Spotify has said this strategy encourages users to upgrade.

However, a sizable chunk of customers continue to circumvent advertisements. Last year, the company said 2 million users (about 1.3% of its total user base at the time) were using an ad blocker of some kind, TechCrunch reported. It’s made other attempts to crackdown on ad blocking, including on Android.

Spotify recently announced it bought podcast companies Gimlet Media and Anchor, further signaling the company’s ambitions for the future.