As the Trump administration agonizes over the leakiness of its White House, chief of staff John Kelly has implemented a new stopgap measure—glorified hall monitors.

Kelly’s ban on personal cell phones in the White House has been in place since January, but a Tuesday CNN report revealed new details about how the ban is executed.

Staffers reportedly leave their phones in lockers during the day, setting off an hours-long chorus of vibrations and rings. To ensure that White House officials have properly stowed their electronics, suit-clad men reportedly sweep the hallways and rooms with handheld devices that can pinpoint prohibited phones. Per CNN, the devices are so savvy that they can differentiate between types of electronic contraband.

Though Kelly has threatened White House bans for any staffer found with an illicit phone, unnamed sources told CNN that few people take that seriously. Some added that the draconian measures did not prevent staffer Kelly Sadler’s off-color joke about Sen. John McCain (R-AZ) “dying anyway” from leaking, the impetus of the recent crackdown.