diff --git a/hardware/arduino/cores/arduino/CDC.cpp b/hardware/arduino/cores/arduino/CDC.cpp
index 3dbf15df3e..3cfd1b7567 100644
--- a/hardware/arduino/cores/arduino/CDC.cpp
+++ b/hardware/arduino/cores/arduino/CDC.cpp
@@ -129,7 +129,7 @@ void Serial_::end(void)
 int Serial_::available(void)
 {
 	if (peek_buffer >= 0) {
-		return 1;
+		return 1 + USB_Available(CDC_RX);
 	}
 	return USB_Available(CDC_RX);
 }