Comcast said that The Office and WWE were to thank for its new-ish streaming service, Peacock, adding 9 million signups during the first three months of 2021. Peacock now has 42 million members total in the United States. That looks strong compared to HBO’s 44.2 million US customers, but it comes with a huge caveat: Peacock has a free tier, and Comcast doesn’t say how many customers are paying.

Still, Peacock got a sizable boost during a quarter when other streaming services notched smaller growth. HBO added 2.7 million subscribers in the US, and Netflix added 4 million subscribers globally. (Disclosure: Comcast is an investor in Vox Media, The Verge’s parent company.)

Two big names contributed to this quarter’s growth. The Office became a Peacock exclusive on January 1st, after leaving Netflix where it had become a staple of comfort viewing. And on March 18th, the WWE Network launched on Peacock, bringing over around a decade of pay-per-views.

The problem will be whether Peacock can keep this up going forward. Those were two big names, and the service didn’t even have a particularly remarkable quarter — it added 11 million signups last quarter, and it added 10 million signups before the service even fully launched. So 9 million, in comparison, during a quarter when it rolled out some huge names, starts to look a little concerning.