diff --git a/libraries/AP_SerialManager/AP_SerialManager.h b/libraries/AP_SerialManager/AP_SerialManager.h
index 8f1eebd771..f9e5890623 100644
--- a/libraries/AP_SerialManager/AP_SerialManager.h
+++ b/libraries/AP_SerialManager/AP_SerialManager.h
@@ -150,6 +150,7 @@ public:
         SerialProtocol_AirSpeed = 34,
         SerialProtocol_ADSB = 35,
         SerialProtocol_AHRS = 36,
+        SerialProtocol_SmartAudio = 37,
         SerialProtocol_NumProtocols                    // must be the last value
     };