diff --git a/led-annunciator/led-annunciator.ino b/led-annunciator/led-annunciator.ino
index 89e8f2b..d454586 100644
--- a/led-annunciator/led-annunciator.ino
+++ b/led-annunciator/led-annunciator.ino
@@ -41,14 +41,15 @@ void setup() {
 void loop() {
 
   // SERIAL
-  while (Serial.available()) {
-    String rcv_sr = Serial.readString();
+  while ( Serial.available() > 0 ) {
+    int rcv_sr = Serial.read();
 
     // Send data to serial port
-    Serial.println("RX serial: " + rcv_sr);
+    Serial.print("RX serial: ");
+    Serial.println(rcv_sr, DEC);
 
     // Switch LEDs
-    switch (rcv_sr[0]) {
+    switch (rcv_sr) {
       case 'g' :
         led_allOff();
         led_greenLine();