diff --git a/drivers/RawSerial.h b/drivers/RawSerial.h
index 1ede0c8a33..4325bcb9e0 100644
--- a/drivers/RawSerial.h
+++ b/drivers/RawSerial.h
@@ -88,6 +88,7 @@ public:
 
     int printf(const char *format, ...);
 
+#if !(DOXYGEN_ONLY)
 protected:
 
     /* Acquire exclusive access to this serial port
@@ -97,6 +98,7 @@ protected:
     /* Release exclusive access to this serial port
      */
     virtual void unlock(void);
+#endif
 };
 
 } // namespace mbed
diff --git a/drivers/Serial.h b/drivers/Serial.h
index 7c5e536acb..1b1e6aa34e 100644
--- a/drivers/Serial.h
+++ b/drivers/Serial.h
@@ -63,10 +63,10 @@ public:
      *  @param tx Transmit pin
      *  @param rx Receive pin
      *  @param name The name of the stream associated with this serial port (optional)
-     *  @param baud The baud rate of the serial port (optional, defaults to MBED_CONF_PLATFORM_DEFAULT_SERIAL_BAUD_RATE)
+     *  @param baud The baud rate of the serial port (optional, defaults to MBED_CONF_PLATFORM_DEFAULT_SERIAL_BAUD_RATE or 9600)
      *
      *  @note
-     *    Either tx or rx may be specified as NC if unused
+     *    Either tx or rx may be specified as NC (Not Connected) if unused
      */
     Serial(PinName tx, PinName rx, const char *name = NULL, int baud = MBED_CONF_PLATFORM_DEFAULT_SERIAL_BAUD_RATE);
 
@@ -78,7 +78,7 @@ public:
      *  @param baud The baud rate of the serial port
      *
      *  @note
-     *    Either tx or rx may be specified as NC if unused
+     *    Either tx or rx may be specified as NC (Not Connected) if unused
      */
     Serial(PinName tx, PinName rx, int baud);
 
@@ -99,6 +99,7 @@ public:
         return SerialBase::writeable();
     }
 
+#if !(DOXYGEN_ONLY)
 protected:
     virtual int _getc();
     virtual int _putc(int c);
@@ -106,6 +107,7 @@ protected:
     virtual void unlock();
 
     PlatformMutex _mutex;
+#endif
 };
 
 } // namespace mbed