Own a drone? Get ready to register it with the FAA.

The Federal Aviation Administration announced that starting later this month, hobbyists will have to register their drones in a national database. There have been more than 700 close calls this year between drones and manned aircraft.

During World War II, fighter pilots sometimes spotted mysterious glowing objects hovering off the wings of their craft. Nicknamed “foo fighters,” the objects, which might have been ball lightning or electrostatic discharge, would appear to chase planes through aerial maneuvers before simply vanishing.

Today, pilots glancing out their windows often see similar objects pursuing them – but these “foo fighters” are drones being piloted by hobbyists on the ground.

There are already plenty of laws on the books regarding where and when drone enthusiasts can fly their craft: they must stay within 400 feet of the ground, for instance, and can’t be within five miles of an airport. But these laws are difficult to enforce, and in August a Federal Aviation Administration report revealed that drones had nearly collided with airplanes on almost 700 occasions in 2015, up from approximately 225 incidents in 2014. In many of those cases, drones buzzed passenger jets as they took off from or landed at major airports.

This week, the FAA announced a new set of rules designed to rein in rogue drones. Starting on December 21, anyone who owns a recreational drone will have to register it in a national database. Users will have to submit their names, home addresses, and e-mail accounts with their registration, a step which the FAA hopes will encourage people to fly their drones responsibly.

“Registration gives us an opportunity to work with these users to operate their unmanned aircraft safely,” Anthony Foxx, secretary of the Transportation Department, told reporters in a conference call Monday.

Hobbyist drones are small enough that they don’t show up on radar, making them difficult to track. And even if a pilot does manage to identify the make and model of a drone as it whizzes by, the drone’s operator could be miles away, which means it’s all but impossible to arrest someone for flying a drone in restricted airspace.

The new rules address that problem in two ways: first, all drones must now display their registration number or serial number, so if the craft hovers near a plane there’s a chance the pilot may be able to report the drone’s markings. Second, the FAA hopes the act of having to register a drone in a database will help impress the rules on hobbyists.

“With the current unprecedented proliferation of new sUAS [small Unmanned Aircraft Systems, or drones], registration allows the FAA a direct and immediate opportunity to educate sUAS owners,” the Administration’s interim rule reads.

Registration will be free from the time it opens on December 21 until January 20, 2016; after that, it will cost users $5 to register each drone. The FAA expects people to buy about 700,000 new drones over the holidays.