diff --git a/libraries/AP_HAL_ChibiOS/hwdef/mRoControlZeroClassic/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/mRoControlZeroClassic/hwdef.dat
index e5896d6027..5267a4abe9 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/mRoControlZeroClassic/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/mRoControlZeroClassic/hwdef.dat
@@ -129,6 +129,9 @@ PB1 AUX_ADC2 ADC1 SCALE(1)
 # And the analog input for airspeed (rarely used these days).
 PC5 PRESSURE_SENS ADC1 SCALE(2)
 
+# Servo rail analog input
+PF13 FMU_SERVORAIL_VCC_SENS ADC2 SCALE(2) 
+
 # RSSI Analog Input
 PC0 RSSI_IN ADC1