diff --git a/conf/firmwares/subsystems/shared/radio_control_spektrum.makefile b/conf/firmwares/subsystems/shared/radio_control_spektrum.makefile
index 9ae8199429..3b3a152067 100644
--- a/conf/firmwares/subsystems/shared/radio_control_spektrum.makefile
+++ b/conf/firmwares/subsystems/shared/radio_control_spektrum.makefile
@@ -1,6 +1,7 @@
 #
 # Makefile for shared radio_control spektrum susbsytem
 #
+# Define USE_DSMX on STM32 microcontrollers to bind in DSMX instead of DSM2
 
 RADIO_CONTROL_LED ?= none