The makers of semi-autonomous driving hardware often tout safety as a big selling point for their technology. But drivers may have to accept that the near future will hold at least a few bumps, and perhaps increased insurance premiums, if the effect of smartphones is anything to go by.

The Wall Street Journal reports that some car insurers are finding that their payouts are rising faster than their premiums. And a chief culprit, according to analysis by State Farm Mutual Automobile Insurance, is smartphones—with over half of drivers aged 18 to 29 admitting to texting and Internet browsing while at the controls of their car. The result: more accidents now occur because people play with their phones, and those incidents are pushing premium prices up.

The problem is more serious than a minor bump every time someone checks Facebook on the highway. Last year, statistics published by the National Highway Traffic Safety Administration showed that the number of fatalities in accidents where distracted driving—the result of, say, texting on a cell phone, but also sipping at an iced coffee—was cited as a reason have risen by 8.8 percent year-on-year, from 3,197 to 3,477.

At the time, Brandon Schoettle from the Transportation Research Institute University of Michigan warned MIT Technology Review that semi-autonomous driving may exacerbate the distracted driving problem further.

Current self-driving systems, such as Autopilot, only work some of the time. When they are unable to process the world around them and make sensible decisions about how to act, they pass control to the driver. But if the human behind the wheel has been overly enjoying the luxury of not having to focus on the road, the hand-off can go badly—or not even happen, as appears to have been the case in last year’s fatal Tesla accident.

Some autonomous car researchers, such as those working on Alphabet’s Waymo self-driving project, have always tended to argue that full autonomy—where drivers never have to control the car—is the safest route to a self-driving future.

Last week, Bloomberg reported that Ford had come to the same conclusion, after its engineers had begun falling asleep at the wheel of its autonomous cars. The automaker believes that providing enough time to wake someone and have them safely take over the task of driving essentially makes semi-autonomous systems inherently dangerous, as road conditions can change in a matter of seconds.

Still, semi-autonomous systems are proving to be popular. Our own Tom Simonite reports that DIY autonomy systems, pieced together with off-the-shelf electronics and free software, are increasingly being used to imbue vehicles with the ability to pilot themselves on highways. But use of such systems, and those provided in production vehicles form the get-go, could, as Schoettle warns, lead to more accidents—and correspondingly higher premiums.

In the long-term, of course, fully autonomous vehicles are likely to make the roads safer—and with that, insurance premiums will likely tumble. But it looks like the situation may get a little worse before it gets much better.

(Read more: Wall Street Journal, Bloomberg, “Semi-Autonomous Cars Could Increase Distracted Driving Deaths,” “Fatal Tesla Autopilot Crash Is a Reminder Autonomous Cars Will Sometimes Screw Up,” “How a College Kid Made His Honda Civic Self-Driving for $700”)