diff --git a/libraries/AP_HAL/RCOutput.h b/libraries/AP_HAL/RCOutput.h
index e78732cac9..f522ec685b 100644
--- a/libraries/AP_HAL/RCOutput.h
+++ b/libraries/AP_HAL/RCOutput.h
@@ -25,6 +25,7 @@
 #define CH_16 15
 #define CH_17 16
 #define CH_18 17
+#define CH_NONE 255
 #endif