diff --git a/boards/iot-lab_M3/include/board.h b/boards/iot-lab_M3/include/board.h
index 2e5965a92d55131e3270294914b22b902cb89d8e..5b2247a697cd5bf0377119fc07d41db6e2756dd5 100644
--- a/boards/iot-lab_M3/include/board.h
+++ b/boards/iot-lab_M3/include/board.h
@@ -39,7 +39,8 @@ extern "C" {
 #define F_CPU               CLOCK_CORECLOCK
 
 /**
- * @name Define the UART to be used as stdio and its baudrate
+ * @name Define the UART to be used as stdio, its baudrate, and the size of
+ *       receiving ringbuffer
  * @{
  */
 #define STDIO               UART_0