Facebook is tweaking the algorithm for picking what videos it shows users in their News Feed to put more emphasis on longer-form clips — a move that comes as the social powerhouse is in talks to fund or license exclusive programming.

The explanation of the change Facebook is making is a bit wonky. It’s adjusting how it ranks videos in News Feed to weight the viewing-completion percentage of a video more heavily the longer a video is. That’s to “avoid penalizing longer videos,” the company said in a blog post, because “we know that completing a longer video is a bigger commitment than completing a shorter one.”

Facebook is making the adjustment because it wants its billion-plus user base to spend more time watching video — and, of course, being exposed to more ads.

The change also comes as Facebook has kicked off an effort to bring a variety of shows, including scripted and unscripted formats and sports programming, from media companies and individual digital stars. Facebook’s goal is to seed content for the new video tab in its mobile app, to make it more of a destination for users to spend time watching video content. The initiative is being headed up by Ricky Van Veen, Facebook’s head of global creative strategy, who joined the social giant earlier this year from CollegeHumor.

So, for multiple reasons, Facebook wants users to be able to more easily find and watch longer videos — whether that’s stuff it has invested in or not. However, just because a video lasts, say, 10 minutes instead of 30 seconds, doesn’t mean it will automatically be rewarded.

Facebook said the priority for creators on the platform should continue to be producing “videos that are relevant and engaging to their audiences,” adding that if people don’t want watch longer videos those won’t be more likely to appear in News Feeds. “The best length for a video is whatever length is required to tell a compelling story that engages people, which is likely to vary depending on the story you’re telling,” the company advised.

Most Facebook partners will not see significant changes in distribution as a result of the News Feed update. However, longer videos that people spend time watching may see a slight increase in distribution on Facebook — and by the same token, some shorter videos may see a modest drop in News Feed distribution, according to Facebook.

Facebook said it will gradually roll out the change to the News Feed algorithm favoring longer-form videos over the next few weeks.

During September 2016, Facebook said it had an average of 1.18 billion daily active users in September, up from 1.01 billion a year earlier. Overall it had 1.79 billion monthly active users in the third quarter, with about 93% of those accessing Facebook from a mobile device.