diff --git a/ArduPlane/GCS_Mavlink.cpp b/ArduPlane/GCS_Mavlink.cpp
index d817339979..f428e8cffd 100644
--- a/ArduPlane/GCS_Mavlink.cpp
+++ b/ArduPlane/GCS_Mavlink.cpp
@@ -798,6 +798,10 @@ bool GCS_MAVLINK::try_send_message(enum ap_message id)
         CHECK_PAYLOAD_SIZE(VIBRATION);
         send_vibration(plane.ins);
         break;
+
+    case MSG_RPM:
+        // unused
+        break;
     }
     return true;
 }