Amazon’s delivery drones are not yet dropping off packages, but the company is already envisioning how else that might be used — including by offering “surveillance as a service.” Amazon was recently granted a patent that outlines how its UAVs could keep an eye on customers’ property between deliveries while supposedly maintaining their privacy.

The patent was originally filed in June 2015 and became public earlier this month. It describes how the company’s drones could be hired to look out for open garage doors, broken windows, graffiti, or even a fire, before alerting the owner of the property.

Drones have long been used for surveillance, particularly by the military, but companies are now beginning to explore how they might be used for home security. However, it’s rare to hear about surveillance being done by delivery drones, which are still in their infancy.

While Alphabet’s Wing has only just been granted FAA approval to make deliveries in the US, Amazon’s new drone, unveiled earlier this month, has not. Amazon says it hopes to launch a commercial service “in a matter of months.”

The patent gives a few hints how the surveillance service could work. It says customers would be allowed to pay for visits on an hourly, daily, or weekly basis, and that drones could be equipped with night vision cameras and microphones to expand their sensing capabilities.

Using delivery drones for surveillance raises huge privacy concerns for everyone who hasn’t given Amazon permission to view their homes — a problem that Amazon’s patent specifically addresses. The patent describes how geo-fencing technology would be used to ensure that Amazon’s drones don’t capture footage of houses they’re not supposed to. Images could be edited during capture or they processed post-capture. Images could also be limited by “physically constraining a sensor of the UAV,” which suggests a drone’s camera may be physically prevented from looking at any unauthorized houses.

Of course, all the usual disclaimers about patents apply — it’s entirely possible that this service will never see the light of day. Amazon has patented some pretty eccentric drone technologies over the years that have never made it to market; including a floating airship that could act as a warehouse for delivery drones, a parachute shipping label, and a system that lets a drone understand when you shout or wave at it.