The fifth-generation cellular network rolling out in America and other countries this year will revolutionize the way our devices connect to the internet and to one another. 5G is such a technologically important leap forward–without it the future smart cities we dream about where everything is connected simply wouldn’t be possible.

However, there is one major–and unavoidable–drawback to 5G: It’s going to cost you your location privacy. Anyone with access to your ISP’s cell tower data will be able to hone in on your exact location far more precisely than they can today under our 4G networks. The reason for this is that 4G network technology has a wide coverage area when it comes to being broadcast from a single cellular tower. Matter of fact, 4G can be broadcast about a mile from a single tower.

5G network technology, on the other hand, has a much smaller coverage area, and it can’t penetrate through walls to get indoors as well as 4G technology can. This means 5G networks will require many more cellular towers placed closer together. These towers won’t be like the old towers you envision that look like electrified Eiffel Towers, mind you, they’re just small antennas that will need to be dotted around on rooftops and street lights and inside shopping malls and other buildings. But at the end of the day, dozens and dozens of 5G towers will need to be placed around an area that a single 4G tower would have covered in the past.

So how does this affect your location privacy? Each time your device connects to a tower, your mobile network knows you are within range of that tower. Under 4G networks, that means your mobile provider could pinpoint your location within about a mile’s accuracy–so your location was pretty well obfuscated. But since 5G towers will need to be everywhere and you’ll only connect to one 5G tower at a time, your mobile network will now be able to pinpoint your location much more accurately–even knowing which building you are in. On top of this, as you move through a city, your mobile network provider will be able to chart the path you take with a high degree of accuracy since your device will keep jumping from connecting to one nearest 5G tower to the next.

Steve Bellovin, a professor of computer science at Columbia University, recently told the Wall Street Journal that 5G will raise privacy concerns when it comes to location data:

5G signals in the U.S. will have a very short range and won’t easily go through buildings. This means there need to be many more cell towers. The main way that a cellphone tells where you are–as opposed to a website or an app–is, which tower are you talking to. Today’s towers have a radius of about a mile. If the new towers cover a much smaller area, it means that they know much more precisely where you are . . . You’re going to see a lot more indoor towers–in shopping malls, big office buildings, hotels and so on. So in that sense you are going to get far more precise.

So what does this lack of location privacy on 5G networks mean to you? If your mobile network sells your data, it will be much easier for data brokers and advertisers to see your current location and target more relevant ads to you based on your location. This data can also enable advertisers and data brokers to see the exact routes you take each day and even which buildings you go into. And anyone with access to your mobile network’s cell tower data will now be able to track your movements in real time.

But unfortunately, if you want 5G service, there’s no way around giving up more of your location privacy. Welcome to the brave new world of 5G.