diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp
index 284d8fc..a0a6642 100644
--- a/cores/arduino/HardwareSerial.cpp
+++ b/cores/arduino/HardwareSerial.cpp
@@ -8,10 +8,13 @@
 #include "wiring_LL.h" 
 
 // HardwareSerial class objects for use in Arduino IDE
-HardwareSerial Serial(0);
+HardwareSerial Serial0(0);
 #if SERIAL_PORT_QTY > 1
 HardwareSerial Serial1(1);
 #endif
+// default interface
+HardwareSerial& Serial = DEFAULT_SERIAL;
+
 
 void serialEvent() __attribute__((weak));
 bool Serial0_available() __attribute__((weak));
@@ -144,7 +147,7 @@ extern "C" void __attribute__((optimize("O3"))) serial_interrupt_handler(uint8_t
 {
   if (uartNumInt == 0)
   {
-    Serial.rx_complete_irq();
+    Serial0.rx_complete_irq();
   }
   else if ((uartNumInt == 1) && (SERIAL_PORT_QTY > 1))
   {
diff --git a/cores/arduino/HardwareSerial.h b/cores/arduino/HardwareSerial.h
index d7f60a1..792bf13 100644
--- a/cores/arduino/HardwareSerial.h
+++ b/cores/arduino/HardwareSerial.h
@@ -103,10 +103,12 @@ class HardwareSerial : public Stream
     inline void rx_complete_irq(void) __attribute__((always_inline, optimize("O3")));
 };
 
-extern HardwareSerial Serial;
+extern HardwareSerial Serial0;
 #if SERIAL_PORT_QTY > 1
 extern HardwareSerial Serial1;
 #endif
+// default interface
+extern HardwareSerial& Serial;
 
 extern void serialEventRun(void) __attribute__((weak));
 
diff --git a/variants/elbear_ace_nano/pins_arduino.h b/variants/elbear_ace_nano/pins_arduino.h
index e04ad86..847bba2 100644
--- a/variants/elbear_ace_nano/pins_arduino.h
+++ b/variants/elbear_ace_nano/pins_arduino.h
@@ -81,6 +81,7 @@ void additionalPinsDeinit(uint32_t PinNumber);
 // UART
 // available uarts quantity
 #define SERIAL_PORT_QTY 2
+#define DEFAULT_SERIAL  Serial0
 
 // ADC
 #define MCU_ADC_RESOLUTION    12 // bits
diff --git a/variants/elbear_ace_uno/pins_arduino.h b/variants/elbear_ace_uno/pins_arduino.h
index dea17b3..045510c 100644
--- a/variants/elbear_ace_uno/pins_arduino.h
+++ b/variants/elbear_ace_uno/pins_arduino.h
@@ -76,6 +76,7 @@ static inline void additionalPinsDeinit(uint32_t PinNumber){}
 // UART
 // available uarts quantity
 #define SERIAL_PORT_QTY 2
+#define DEFAULT_SERIAL  Serial0
 
 // ADC
 #define MCU_ADC_RESOLUTION    12 // bits
diff --git a/variants/elsomik/pins_arduino.h b/variants/elsomik/pins_arduino.h
index af3c02a..19afe33 100644
--- a/variants/elsomik/pins_arduino.h
+++ b/variants/elsomik/pins_arduino.h
@@ -109,6 +109,7 @@ static inline void additionalPinsDeinit(uint32_t PinNumber){}
 // UART
 // available uarts quantity
 #define SERIAL_PORT_QTY 2
+#define DEFAULT_SERIAL  Serial0
 
 // ADC
 #define MCU_ADC_RESOLUTION    12 // bits
diff --git a/variants/start/pins_arduino.h b/variants/start/pins_arduino.h
index d3c7aa4..59c310b 100644
--- a/variants/start/pins_arduino.h
+++ b/variants/start/pins_arduino.h
@@ -122,6 +122,7 @@ static inline void additionalPinsDeinit(uint32_t PinNumber){}
 // UART
 // available uarts quantity
 #define SERIAL_PORT_QTY 2
+#define DEFAULT_SERIAL  Serial0
 
 // ADC
 #define MCU_ADC_RESOLUTION    12 // bits