BOARD_HAS_USB_SERIAL undefined for Arduino Uno

[djipco]

Maybe there's something I don't understand but shouldn't BOARD_HAS_USB_SERIAL be defined on an Arduino Uno r3?

I have this code in my library and when I run it on an Arduino Uno, SLIPEncodedSerial.h is the one that gets included. Am I missing something obvious or this is not the correct bahaviour?

#include "OSC/OSCBoards.h"
#include "OSC/OSCMessage.h"

#ifdef BOARD_HAS_USB_SERIAL
#include "OSC/SLIPEncodedUSBSerial.h"
SLIPEncodedUSBSerial SLIPSerial(thisBoardsSerialUSB);
#else
#include "OSC/SLIPEncodedSerial.h"
SLIPEncodedSerial SLIPSerial(Serial);
#endif

Thanks for your help.