YouTube has been going after people who block ads for a while now. It used to only go after ad-blockers, but now YouTube is going after apps on your phone or computer that let you watch YouTube without ads as well.

“Ad blockers are against YouTube’s Terms of Service,” a Google representative told cord cutters news when the crackdown began. “We’ve started a worldwide campaign to get people who use ad blockers to either let ads show on YouTube or try YouTube Premium to watch videos without ads.” Ads help a wide range of artists around the world and give billions of people access to their favorite YouTube videos.

READ MORE: YouTube TV Is Launching An Updated Library For Your DVR

Now YouTube has said that it will crack down on phone apps that do the same thing.

Hi everyone, 

We’re strengthening our enforcement on third-party apps that violate YouTube’s Terms of Service, specifically ad-blocking apps. 

Viewers who are using these third-party apps may experience buffering issues or see the error “The following content is not available on this app” when trying to watch a video. We want to emphasize that our terms don’t allow third-party apps to turn off ads because that prevents the creator from being rewarded for viewership, and Ads on YouTube help support creators and let billions of people around the world use the streaming service. We also understand that some people prefer an entirely ad-free experience, which is why we offer YouTube Premium.

We only allow third-party apps to use our API when they follow our API Services Terms of Service, and when we find an app that violates these terms, we will take appropriate action to protect our platform, creators, and viewers.

READ MORE: YouTube Is Testing AI That Can Skip Boring Parts Of Videos

This comes as YouTube tries to get more people to sign up for YouTube Premium, which removes ads and adds features like the ability to watch videos offline. But since the beginning of this year, YouTube paid has been getting in touch with users who seem to be giving their paid subscriptions to other people. They told the customers in the emails (an sample can be seen HERE on Reddit) that they think they shared their passwords. If the owner doesn’t answer the email and agree to stop sharing, YouTube will cancel their Premium account.

As a result of all of this, YouTube has been working harder to stop people from using ad-blockers on its site, since those add-ons are against the rules. Earlier this year, the company talked about a “global effort” to get rid of them.

READ MORE: The TikTokification Of YouTube And Vice Versa: How Streaming Is Converging

It is working to get rid of ad-blockers, which take away from its ad-based income. Google made $7.95 billion from ads on YouTube in the third quarter, up from $7.07 billion in the same period last year.

The crackdown on ad blockers is also meant to get people to pay for YouTube Premium. Users have been able to switch to the Premium tier over and over again on the site.

For $13.99 a month, YouTube Premium users can watch videos without ads. There are also family and school plans available. Customers who have a subscription can also access YouTube Music Premium and download videos to watch when they don’t have internet access.