diff --git a/firmware/config/boards/proteus/board.mk b/firmware/config/boards/proteus/board.mk
index 8ca761254e..b04872bd2a 100644
--- a/firmware/config/boards/proteus/board.mk
+++ b/firmware/config/boards/proteus/board.mk
@@ -23,6 +23,9 @@ DDEFS += -DEFI_CAN_SERIAL=TRUE
 # Turn off stuff proteus doesn't have/need
 DDEFS += -DEFI_CJ125=FALSE -DEFI_MAX_31855=FALSE -DBOARD_L9779_COUNT=0 -DBOARD_TLE8888_COUNT=0 -DEFI_HD44780_LCD=FALSE -DEFI_LCD=FALSE 
 
+# Any Proteus-based adapter boards with discrete-VR decoder are controlled via a 5v ignition output
+DDEFS += -DVR_SUPPLY_VOLTAGE=5
+
 # This stuff doesn't work on H7 yet
 ifneq ($(PROJECT_CPU),ARCH_STM32H7)
 	DDEFS += -DSTM32_ADC_USE_ADC3=TRUE
diff --git a/firmware/controllers/sensors/vr_pwm.cpp b/firmware/controllers/sensors/vr_pwm.cpp
index f3996ea12f..52ddb362c9 100644
--- a/firmware/controllers/sensors/vr_pwm.cpp
+++ b/firmware/controllers/sensors/vr_pwm.cpp
@@ -5,6 +5,11 @@
 static OutputPin pins[VR_THRESHOLD_COUNT];
 static SimplePwm pwms[VR_THRESHOLD_COUNT];
 
+// Default to 3.3v if not defined, most boards wire the VR threshold input directly to an MCU pin.
+#ifndef VR_SUPPLY_VOLTAGE
+#define VR_SUPPLY_VOLTAGE 3.3f
+#endif
+
 static void updateVrPwm(int rpm, size_t index) {
 	auto& cfg = engineConfiguration->vrThreshold[index];
 
@@ -16,7 +21,9 @@ static void updateVrPwm(int rpm, size_t index) {
 
 	// 0v   threshold voltage = 3.3v output from mcu = 100% duty
 	// 2.5v threshold voltage = 0v   output from mcu = 0% duty
-	float duty = interpolateClamped(0, 1, 2.5f, 0, thresholdVoltage);
+	float thresholdInputVoltage = interpolateClamped(0, 3.3f, 2.5f, 0, thresholdVoltage);
+
+	float duty = thresholdInputVoltage / VR_SUPPLY_VOLTAGE;
 
 	pwms[index].setSimplePwmDutyCycle(duty);
 }