diff --git a/libraries/AP_HAL/RCOutput.h b/libraries/AP_HAL/RCOutput.h
index aa27d92ca5..8cb9694489 100644
--- a/libraries/AP_HAL/RCOutput.h
+++ b/libraries/AP_HAL/RCOutput.h
@@ -4,6 +4,9 @@
 
 #include "AP_HAL_Namespace.h"
 
+#define RC_OUTPUT_MIN_PULSEWIDTH 400
+#define RC_OUTPUT_MAX_PULSEWIDTH 2100
+
 /* Define the CH_n names, indexed from 1, if we don't have them already */
 #ifndef CH_1
 #define CH_1 0