diff --git a/hardware/arduino/avr/cores/arduino/Arduino.h b/hardware/arduino/avr/cores/arduino/Arduino.h
index 6b923a46f..630f0d6d7 100644
--- a/hardware/arduino/avr/cores/arduino/Arduino.h
+++ b/hardware/arduino/avr/cores/arduino/Arduino.h
@@ -118,6 +118,7 @@ typedef uint8_t boolean;
 typedef uint8_t byte;
 
 void init(void);
+void initVariant(void);
 
 void pinMode(uint8_t, uint8_t);
 void digitalWrite(uint8_t, uint8_t);
diff --git a/hardware/arduino/avr/cores/arduino/main.cpp b/hardware/arduino/avr/cores/arduino/main.cpp
index 0ad696215..091c365fc 100644
--- a/hardware/arduino/avr/cores/arduino/main.cpp
+++ b/hardware/arduino/avr/cores/arduino/main.cpp
@@ -19,10 +19,17 @@
 
 #include <Arduino.h>
 
+// Weak empty variant initialization function.
+// May be redefined by variant files.
+void initVariant() __attribute__((weak));
+void initVariant() { }
+
 int main(void)
 {
 	init();
 
+	initVariant();
+
 #if defined(USBCON)
 	USBDevice.attach();
 #endif