diff --git a/cores/arduino/HID.cpp b/cores/arduino/HID.cpp
index 378a157..e7ee249 100644
--- a/cores/arduino/HID.cpp
+++ b/cores/arduino/HID.cpp
@@ -201,7 +201,15 @@ bool WEAK HID_Setup(Setup& setup)
 //================================================================================
 //	Mouse
 
-Mouse_::Mouse_() : _buttons(0)
+Mouse_::Mouse_(void) : _buttons(0)
+{
+}
+
+void Mouse_::begin(void) 
+{
+}
+
+void Mouse_::end(void) 
 {
 }
 
@@ -253,7 +261,15 @@ bool Mouse_::isPressed(uint8_t b)
 //================================================================================
 //	Keyboard
 
-Keyboard_::Keyboard_() 
+Keyboard_::Keyboard_(void) 
+{
+}
+
+void Keyboard_::begin(void) 
+{
+}
+
+void Keyboard_::end(void) 
 {
 }
 
diff --git a/cores/arduino/USBAPI.h b/cores/arduino/USBAPI.h
index 05f7318..c8948c1 100644
--- a/cores/arduino/USBAPI.h
+++ b/cores/arduino/USBAPI.h
@@ -57,7 +57,9 @@ private:
 	uint8_t _buttons;
 	void buttons(uint8_t b);
 public:
-	Mouse_();
+	Mouse_(void);
+	void begin(void);
+	void end(void);
 	void click(uint8_t b = MOUSE_LEFT);
 	void move(signed char x, signed char y, signed char wheel = 0);	
 	void press(uint8_t b = MOUSE_LEFT);		// press LEFT by default
@@ -121,7 +123,9 @@ private:
 	KeyReport _keyReport;
 	void sendReport(KeyReport* keys);
 public:
-	Keyboard_();
+	Keyboard_(void);
+	void begin(void);
+	void end(void);
 	virtual size_t write(uint8_t k) {return type(k);};
 	virtual size_t type(uint8_t k);
 	virtual size_t press(uint8_t k);