diff --git a/lib/uart.js b/lib/uart.js
index a142c18..0912bc1 100644
--- a/lib/uart.js
+++ b/lib/uart.js
@@ -235,7 +235,7 @@ class BluetoothHciSocket extends EventEmitter {
 
   write (data) {
     debug(`Write: ${data.toString('hex')}`);
-    if (this._mode === 'raw' || this._mode === 'user') {
+    if ((this._mode === 'raw' || this._mode === 'user') && this._queue) {
       this._queue.push(data);
     }
   }