diff --git a/libraries/AP_Frsky_Telem/AP_Frsky_SPort.cpp b/libraries/AP_Frsky_Telem/AP_Frsky_SPort.cpp
index c4dd68e481..ee22bc40de 100644
--- a/libraries/AP_Frsky_Telem/AP_Frsky_SPort.cpp
+++ b/libraries/AP_Frsky_Telem/AP_Frsky_SPort.cpp
@@ -43,7 +43,10 @@ void AP_Frsky_SPort::send(void)
     }
 
     for (int16_t i = 0; i < numc; i++) {
-        int16_t readbyte = _port->read();
+        uint8_t readbyte;
+        if (!_port->read(readbyte)) {
+            break;
+        }
         if (_SPort.sport_status == false) {
             if  (readbyte == FRAME_HEAD) {
                 _SPort.sport_status = true;