Despite spending billions on original content — supposedly in the neighborhood of $12 billion this year, according to Variety — Netflix’s number one show is not any of the ones it’s created in-house. Or even a show that’s still on the air. It’s reruns of The Office, which ended its initial stint on NBC back in 2013. Six years later, The Office still reigns supreme, at least on Netflix.

That’s according to the Wall Street Journal, which writes that The Office may eventually vanish from Netflix, because the show’s owner, NBCUniversal, is starting up a competitive streaming service:

Netflix Inc. may soon have to contemplate life without its No. 1 show. It’s The Office. NBCUniversal, which owns the show, licensed reruns of the comedy to the streaming-video giant years ago. Now NBCUniversal is launching its own streaming service, and has begun internal discussions about removing The Office from Netflix when the contract expires in 2021, according to people familiar with the situation.

The Office’s viewership numbers eclipsed those of Friends, the even-older syndicated sitcom that has remained so popular on Netflix that the service paid $100 million to keep the show available for just one more year after the licensing deal for the series was set to expire.

The Journal says that (according to a Nielsen report) the most-watched Netflix originals were Orange Is the New Black and Ozark, but that their numbers lagged far behind licensed stuff like The Office, Friends, and Grey’s Anatomy. And that’s an issue for Netflix as more and more companies launch their own streaming services and fewer and fewer are willing to license their content to Netflix — or charge Netflix higher and higher fees for the ones they’re willing to part with.

Netflix has made some fairly big hits, and they’re spending so much money on original content that their library is growing rapidly. But if the shows and movies people love and really want to watch aren’t here, will people keep subscribing? Time will tell.

UPDATE: Netflix provided this comment on this article:

"Looking at overall watch time skews towards titles with many seasons. Most Netflix originals have three or fewer seasons at most. It's why we focus on the individual shows or films members watch, as opposed to how much time they spend on one series versus another. And if you look at most watched titles, Netflix originals accounted for 10 out of 10 in the last quarter, or 21 out of the top 25."