diff --git a/src/system.cpp b/src/system.cpp
index 9750fbe03..2ebe27f32 100644
--- a/src/system.cpp
+++ b/src/system.cpp
@@ -231,7 +231,9 @@ void System::start() {
     Mqtt::subscribe("cmd", std::bind(&System::mqtt_commands, this, _1));
 
 #ifndef EMSESP_FORCE_SERIAL
-    EMSuart::start(tx_mode_); // start UART
+    if (tx_mode_) {
+        EMSuart::start(tx_mode_); // start UART, if tx_mode is not 0
+    }
 #endif
 }