diff --git a/cores/arduino/main.cpp b/cores/arduino/main.cpp
index 3c46f1e..ba00ae0 100755
--- a/cores/arduino/main.cpp
+++ b/cores/arduino/main.cpp
@@ -5,6 +5,10 @@ int main(void)
 {
 	init();
 
+#if defined(USBCON)
+	USB.attach();
+#endif
+	
 	setup();
     
 	for (;;)