diff --git a/packages/xod-client-electron/src/app/main.js b/packages/xod-client-electron/src/app/main.js
index 81a77db0..b36de1b3 100644
--- a/packages/xod-client-electron/src/app/main.js
+++ b/packages/xod-client-electron/src/app/main.js
@@ -240,7 +240,8 @@ const onReady = () => {
     )
   );
   ipcMain.on(EVENTS.DEBUG_SERIAL_SEND, (event, str) => {
-    if (!debugPort) return;
+    if (!debugPort || !debugPort.write) return;
+
     debugPort.write(str);
   });
   ipcMain.on(EVENTS.STOP_DEBUG_SESSION, stopDebugSession);