diff --git a/src/backend/UsbTnc.scala b/src/backend/UsbTnc.scala
index 4224de0..72fbe4f 100644
--- a/src/backend/UsbTnc.scala
+++ b/src/backend/UsbTnc.scala
@@ -49,7 +49,7 @@ class UsbTnc(service : AprsService, prefs : PrefsWrapper) extends AprsBackend(pr
 	var alreadyRunning = false
 
 	val intent = new Intent(USB_PERM_ACTION)
-	val pendingIntent = PendingIntent.getBroadcast(service, 0, intent, PendingIntent.FLAG_IMMUTABLE)
+	val pendingIntent = PendingIntent.getBroadcast(service, 0, intent, PendingIntent.FLAG_MUTABLE)
 
 	val receiver = new BroadcastReceiver() {
 		override def onReceive(ctx : Context, i : Intent) {
@@ -59,6 +59,11 @@ class UsbTnc(service : AprsService, prefs : PrefsWrapper) extends AprsBackend(pr
 				ctx.stopService(AprsService.intent(ctx, AprsService.SERVICE))
 				return
 			}
+			if (i.getExtras() == null) {
+                                /* this shouldn't ever happen, don't need i18n */
+				service.postAbort("USB permission bug")
+				return
+			}
 			val granted = i.getExtras().getBoolean(UsbManager.EXTRA_PERMISSION_GRANTED)
 			if (!granted) {
 				service.postAbort(service.getString(R.string.p_serial_noperm))