It was recently reported that 54% of Facebook users access the social network via mobile devices, and now as the company readies its IPO, the issue of how its ad business is affected by mobile use was mentioned in its latest filing with the SEC.

Facebook founder Mark Zuckerberg, terrifying old-timey investors whilst making rounds in his security-hoodie, has along with other execs pointed out how the growth in mobile use of the site can affect the future worth of the Social Network, which is presently shooting for a $96 billion valuation. While Facebook has recently commenced adding sponsored stories to mobile news feeds, it’s still clear that more mobile essentially equates to less ads, which is Facebook’s bread and butter.

A recent comScore report has shown that in March, Facebookers spent about 441 minutes accessing the site via their phones, while only spending 391 minutes via their desktops. This gap is expected to grow, and Facebook is going to have to figure out how to better handle mobile ad content. The market is obviously established, ads just need to be better adapted for handhelds.