diff --git a/rpitx.py b/rpitx.py
index 200a2533..37da585b 100644
--- a/rpitx.py
+++ b/rpitx.py
@@ -294,7 +294,7 @@ if __name__ == "__main__":
 	ser = serial.Serial("/dev/ttyAMA0", 9600)
 	print(ser.portstr)
 	for i in range(6):
-		ser.write("AT+DMOSETGROUP=0,435.0000,434.9100,0,3,0,0\r\n")
+		ser.write(b"AT+DMOSETGROUP=0,435.0000,434.9100,0,3,0,0\r\n")
 		sleep(0.1)
 	ser.close()