Thanks to smartphones, we’re more plugged into the world than ever before. Some of us receive notifications for everything from Amber Alerts to trending news stories, so it makes sense that we’d also depend on our phones to alert us to emergencies in our neighborhoods. But as The Daily Dot reports, relying on your cell phone alone for such news might leave you in a dangerous situation.

Unlike Amber Alerts, local notifications for natural disasters like wildfires don’t operate on a broad alert system. If counties were to contact every single resident every time a specific area was threatened, it would lead to traffic jams and unnecessary panic, putting more lives at risk. So instead, the police only contact people in their database that live in the affected location.

The Reverse 911 law allows law enforcement to contact you at your home in case of emergencies. If you have a landline you can expect to get the call there, but because the law was enacted before the age of cell phones, receiving a call anywhere else isn’t guaranteed. To make sure your county knows to contact you on your cell phone, you need to reach out to them and ask for that number to be listed as your primary mode of contact. Just over half of all households in the country use cell phones for all personal phone communications, which means that most Americans need to opt in to receive life-saving emergency notifications.

Fortunately, getting your cell number into your county’s database isn’t hard. You can starting by searching your county’s name and “emergency alert” online. There’s no uniform system across the U.S., but on Los Angeles County’s emergency alert page, for example, residents are asked to indicate their name, address, phone number, and the type of alerts they wish to receive. This information can be updated at any time—so if you get a new phone number, make sure your local police department is one of the first to know.

[h/t The Daily Dot]