MOUNTAIN VIEW, Calif. – Fair warning, adult website owners: Starting Jan. 10, 2017, ads that pop up on mobile device screens may damage your Google rank.

According to a post on Google’s Webmaster Central Blog, over the past two years 85 percent of webpages have come into compliance with Google’s criteria for “mobile-friendly.” The search giant is pleased with the way sites look and perform on mobile devices.

However, Googgle is not pleased with the number of sites that employ “intrusive interstitials.” The search god defines “intrusive interstitial” as anything that gets in the surfer’s way between the SERP link and the webpage the surfer intended to visit.

“This can frustrate users, because they are unable to easily access the content that they were expecting when they tapped on the search result,” Product Manager Doantam Phan wrote in the post.

“Pages that show intrusive interstitials provide a poorer experience to users than other pages where content is immediately accessible. This can be problematic on mobile devices where screens are often smaller,” he continued. “To improve the mobile search experience, after Jan. 10, 2017, pages where content is not easily accessible to a user on the transition from the mobile search results may not rank as highly.”

All of that is Google’s passive-aggressive way of saying, “We’re fed up with the pop-up ads, people!”

As usual when Google makes a change, the explanation leaves plenty of wiggle room. Essentially, anything that pops onto the screen when the user first lands or while he’s sifting through the contents may lower a page’s rank. The same is true for full-page interstitials users must actively dismiss before they can view the content. Last but not least, anything that appears to be interstitial-like — collapsing ads, for example — “above the fold” on a page may get the website spanked, as well.

Some exceptions are allowed when used responsibly: pop-ups for age-verification, log-in screens, and legal notices, for example. Banners that take up a reasonable amount of screen space and are easily dismissible may be acceptable, too.

All of the phrases in italics represent wiggle room. Google often wiggles when dealing with adult content. It’s safe to say adult websites may as well start rethinking tactics now, because it’s reasonable to assume Google may appear to be picking on the adult industry again — responsibly — come January.