diff --git a/src/modules/commander/commander.cpp b/src/modules/commander/commander.cpp
index 79d0811b72..b6a2846773 100644
--- a/src/modules/commander/commander.cpp
+++ b/src/modules/commander/commander.cpp
@@ -1494,6 +1494,18 @@ int commander_thread_main(int argc, char *argv[])
 
 				/* copy avionics voltage */
 				status.avionics_power_rail_voltage = system_power.voltage5V_v;
+
+				if (status.usb_connected && !system_power.usb_connected) {
+					/*
+					 * apparently the USB cable went away but we are still powered,
+					 * so lets reset to a classic non-usb state.
+					 */
+					usleep(100000);
+					mavlink_log_critical(mavlink_fd, "USB disconnected, rebooting.")
+					usleep(400000);
+					px4_systemreset(false);
+				}
+
 				status.usb_connected = system_power.usb_connected;
 			}
 		}
diff --git a/src/modules/commander/state_machine_helper.cpp b/src/modules/commander/state_machine_helper.cpp
index d44f1f3506..3b169068d4 100644
--- a/src/modules/commander/state_machine_helper.cpp
+++ b/src/modules/commander/state_machine_helper.cpp
@@ -737,5 +737,12 @@ int prearm_check(const struct vehicle_status_s *status, const int mavlink_fd)
 		checkAirspeed = true;
 	}
 
-	return !Commander::preflightCheck(mavlink_fd, true, true, true, true, checkAirspeed, !(status->rc_input_mode == vehicle_status_s::RC_IN_MODE_OFF), !status->circuit_breaker_engaged_gpsfailure_check, true);
+	bool prearm_ok = Commander::preflightCheck(mavlink_fd, true, true, true, true, checkAirspeed, !(status->rc_input_mode == vehicle_status_s::RC_IN_MODE_OFF), !status->circuit_breaker_engaged_gpsfailure_check, true);
+
+	if (status->usb_connected) {
+		prearm_ok = false;
+		mavlink_log_critical(mavlink_fd, "NOT ARMING: Flying with USB connected prohibited");
+	}
+
+	return !prearm_ok;
 }