diff --git a/hardware/arduino/avr/cores/arduino/HardwareSerial.cpp b/hardware/arduino/avr/cores/arduino/HardwareSerial.cpp
index a634b2892..b9dce07cd 100644
--- a/hardware/arduino/avr/cores/arduino/HardwareSerial.cpp
+++ b/hardware/arduino/avr/cores/arduino/HardwareSerial.cpp
@@ -171,7 +171,7 @@ int HardwareSerial::read(void)
     return -1;
   } else {
     unsigned char c = _rx_buffer[_rx_buffer_tail];
-    _rx_buffer_tail = (BUFPOINTER)(_rx_buffer_tail + 1) % SERIAL_RX_BUFFER_SIZE;
+    _rx_buffer_tail = (rx_buffer_index_t)(_rx_buffer_tail + 1) % SERIAL_RX_BUFFER_SIZE;
     return c;
   }
 }
@@ -207,7 +207,7 @@ size_t HardwareSerial::write(uint8_t c)
     sbi(*_ucsra, TXC0);
     return 1;
   }
-  BUFPOINTER i = (_tx_buffer_head + 1) % SERIAL_TX_BUFFER_SIZE;
+  tx_buffer_index_t i = (_tx_buffer_head + 1) % SERIAL_TX_BUFFER_SIZE;
 	
   // If the output buffer is full, there's nothing for it other than to 
   // wait for the interrupt handler to empty it a bit
diff --git a/hardware/arduino/avr/cores/arduino/HardwareSerial.h b/hardware/arduino/avr/cores/arduino/HardwareSerial.h
index e21e55ba7..b96e5d058 100644
--- a/hardware/arduino/avr/cores/arduino/HardwareSerial.h
+++ b/hardware/arduino/avr/cores/arduino/HardwareSerial.h
@@ -32,7 +32,7 @@
 // using a ring buffer (I think), in which head is the index of the location
 // to which to write the next incoming character and tail is the index of the
 // location from which to read.
-#if !(defined(SERIAL_TX_BUFFER_SIZE)&&defined(SERIAL_RX_BUFFER_SIZE))
+#if !(defined(SERIAL_TX_BUFFER_SIZE) && defined(SERIAL_RX_BUFFER_SIZE))
 #if (RAMEND < 1000)
 #define SERIAL_TX_BUFFER_SIZE 16
 #define SERIAL_RX_BUFFER_SIZE 16
@@ -41,10 +41,15 @@
 #define SERIAL_RX_BUFFER_SIZE 64
 #endif
 #endif
-#if (SERIAL_TX_BUFFER_SIZE>255) || (SERIAL_RX_BUFFER_SIZE>255)
-#define BUFPOINTER uint16_t
+#if (SERIAL_TX_BUFFER_SIZE>256)
+typedef uint16_t tx_buffer_index_t;
 #else
-#define BUFPOINTER uint8_t
+typedef uint8_t tx_buffer_index_t;
+#endif
+#if  (SERIAL_RX_BUFFER_SIZE>256)
+typedef uint16_t rx_buffer_index_t;
+#else
+typedef uint8_t rx_buffer_index_t;
 #endif
 
 // Define config for Serial.begin(baud, config);
@@ -85,10 +90,10 @@ class HardwareSerial : public Stream
     // Has any byte been written to the UART since begin()
     bool _written;
 
-    volatile BUFPOINTER _rx_buffer_head;
-    volatile BUFPOINTER _rx_buffer_tail;
-    volatile BUFPOINTER _tx_buffer_head;
-    volatile BUFPOINTER _tx_buffer_tail;
+    volatile rx_buffer_index_t _rx_buffer_head;
+    volatile rx_buffer_index_t _rx_buffer_tail;
+    volatile tx_buffer_index_t _tx_buffer_head;
+    volatile tx_buffer_index_t _tx_buffer_tail;
 
     // Don't put any members after these buffers, since only the first
     // 32 bytes of this struct can be accessed quickly using the ldd