diff --git a/cores/arduino/analog.cpp b/cores/arduino/analog.cpp
index cd61c281f..dd1de77f1 100644
--- a/cores/arduino/analog.cpp
+++ b/cores/arduino/analog.cpp
@@ -570,13 +570,17 @@ float analogReference() {
       case ADC_VREF_CONTROL_VREFH0_AVSS0:
         // the user must know the voltage he applies from outside
         return NAN;
+#ifdef AR_INTERNAL_VOLTAGE
+      case ADC_VREF_CONTROL_IVREF_AVSS0:
+        return AR_INTERNAL_VOLTAGE;
+#endif
       default:
         #if defined(AVCC_MEASURE_PIN)
         if (aref == 0) {
           analogReference(AR_INTERNAL);
           delayMicroseconds(5);
           for (int i = 0; i < 10; i++) {
-            aref += analogRead(AVCC_MEASURE_PIN) * 1.43f  * AVCC_MULTIPLY_FACTOR / (1 << _analogRequestedReadResolution);
+            aref += analogRead(AVCC_MEASURE_PIN) * AR_INTERNAL_VOLTAGE * AVCC_MULTIPLY_FACTOR / (1 << _analogRequestedReadResolution);
           }
           aref = aref / 10;
           analogReference(AR_DEFAULT);
diff --git a/variants/MINIMA/pins_arduino.h b/variants/MINIMA/pins_arduino.h
index c8c08f807..be936298a 100644
--- a/variants/MINIMA/pins_arduino.h
+++ b/variants/MINIMA/pins_arduino.h
@@ -156,6 +156,8 @@ static const uint8_t SS  =  PIN_SPI_CS;
 #define AVCC_MEASURE_PIN        20
 #define AVCC_MULTIPLY_FACTOR    8.33
 
+#define AR_INTERNAL_VOLTAGE     1.43f
+
 #define USB_VID           (0x2341)
 #define USB_PID           (0x0069)
 #define USB_NAME          "UNO R4 Minima"
diff --git a/variants/PORTENTA_C33/pins_arduino.h b/variants/PORTENTA_C33/pins_arduino.h
index e7eecf25f..898a1940d 100644
--- a/variants/PORTENTA_C33/pins_arduino.h
+++ b/variants/PORTENTA_C33/pins_arduino.h
@@ -207,3 +207,5 @@ static const uint8_t SS  =  PIN_SPI_CS;
 #define SerialLoRa          Serial3
 
 #define RTC_CLOCK_SOURCE    RTC_CLOCK_SOURCE_SUBCLK
+
+#define AR_INTERNAL_VOLTAGE     1.18f
\ No newline at end of file
diff --git a/variants/UNOWIFIR4/pins_arduino.h b/variants/UNOWIFIR4/pins_arduino.h
index 755b642bf..4f0ebb897 100644
--- a/variants/UNOWIFIR4/pins_arduino.h
+++ b/variants/UNOWIFIR4/pins_arduino.h
@@ -158,6 +158,8 @@ static const uint8_t SS  =  PIN_SPI_CS;
 #define AVCC_MEASURE_PIN        20
 #define AVCC_MULTIPLY_FACTOR    8.33
 
+#define AR_INTERNAL_VOLTAGE     1.43f
+
 #define USB_VID           (0x2341)
 #define USB_PID           (0x006D)
 #define USB_NAME          "UNO R4 WiFi"