diff --git a/rpitx.py b/rpitx.py
index 48f98ac9..57c52a96 100644
--- a/rpitx.py
+++ b/rpitx.py
@@ -79,6 +79,7 @@ if __name__ == "__main__":
 			print("Can't read callsign from sim.cfg file, defaulting to AMSAT")		
 	print(callsign)
 	GPIO.setmode(GPIO.BCM)  # added to make Tx LED work on Pi 4
+	GPIO.setup(txLed, GPIO.OUT)
 	
 	sleep(1)
 	output(txLed, txLedOn)