diff --git a/libraries/RC_Channel/RC_Channel.h b/libraries/RC_Channel/RC_Channel.h
index 5b8aad1026..9a396b0070 100644
--- a/libraries/RC_Channel/RC_Channel.h
+++ b/libraries/RC_Channel/RC_Channel.h
@@ -240,6 +240,9 @@ public:
         AIRBRAKE =           210, // manual airbrake control
         WALKING_HEIGHT =     211, // walking robot height input
 
+        // inputs 248-249 are reserved for the Skybrush fork at
+        // https://github.com/skybrush-io/ardupilot
+
         // inputs for the use of onboard lua scripting
         SCRIPTING_1 =        300,
         SCRIPTING_2 =        301,