diff --git a/src/drivers/stm32/adc/adc.cpp b/src/drivers/stm32/adc/adc.cpp
index cd2213f450..541abce421 100644
--- a/src/drivers/stm32/adc/adc.cpp
+++ b/src/drivers/stm32/adc/adc.cpp
@@ -68,6 +68,7 @@
 #include <uORB/topics/adc_report.h>
 
 #if defined(ADC_CHANNELS)
+
 /*
  * Register accessors.
  * For now, no reason not to just use ADC1.
@@ -347,16 +348,19 @@ ADC::update_system_power(hrt_abstime now)
 
 	system_power.voltage5V_v = 0;
 
-#if defined(ADC_5V_RAIL_SENSE)
+	/* HW provides ADC_SCALED_V5_SENSE */
+
+#  if defined(ADC_SCALED_V5_SENSE)
 
 	for (unsigned i = 0; i < _channel_count; i++) {
-		if (_samples[i].am_channel == ADC_5V_RAIL_SENSE) {
+		if (_samples[i].am_channel == ADC_SCALED_V5_SENSE) {
 			// it is 2:1 scaled
-			system_power.voltage5V_v = _samples[i].am_data * (6.6f / 4096);
+			system_power.voltage5V_v = _samples[i].am_data * (ADC_V5_V_FULL_SCALE / 4096);
+			break;
 		}
 	}
 
-#endif
+#  endif
 
 	/* Note once the board_config.h provides BOARD_ADC_USB_CONNECTED,
 	 * It must provide the true logic GPIO BOARD_ADC_xxxx macros.