Portable chargers and power banks might be useful additions to your carry-on luggage, but they’re also a potential fire risk. Now Southwest Airlines is tightening rules around their use on board aircraft.

Beware, Southwest Airlines travelers: You’re going to have to keep your portable charging devices visible during flights. Southwest announced the changes in a statement earlier in the week. The new safety measure should allow for flight attendants to address any fires that break out mid-flight quickly.

Passengers on Southwest Airlines flights will soon be required to keep their portable chargers in plain sight while using them because of concerns about the growing number of lithium battery fires.