diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp
index 7b056e9..e40bfbc 100644
--- a/cores/arduino/HardwareSerial.cpp
+++ b/cores/arduino/HardwareSerial.cpp
@@ -49,59 +49,17 @@
 #endif
 #endif
 
-// Define constants and variables for buffering incoming serial data.  We're
-// 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 (RAMEND < 1000)
-  #define SERIAL_BUFFER_SIZE 16
-#else
-  #define SERIAL_BUFFER_SIZE 64
-#endif
-
-struct ring_buffer
+inline void store_char(unsigned char c, HardwareSerial *s)
 {
-  unsigned char buffer[SERIAL_BUFFER_SIZE];
-  volatile uint8_t head;
-  volatile uint8_t tail;
-};
-
-#if SERIAL_BUFFER_SIZE > 256
-#error Serial buffer size too big for head and tail pointers
-#endif
-
-#if defined(USBCON)
-  ring_buffer rx_buffer = { { 0 }, 0, 0};
-  ring_buffer tx_buffer = { { 0 }, 0, 0};
-#endif
-#if defined(UBRRH) || defined(UBRR0H)
-  ring_buffer rx_buffer  =  { { 0 }, 0, 0 };
-  ring_buffer tx_buffer  =  { { 0 }, 0, 0 };
-#endif
-#if defined(UBRR1H)
-  ring_buffer rx_buffer1  =  { { 0 }, 0, 0 };
-  ring_buffer tx_buffer1  =  { { 0 }, 0, 0 };
-#endif
-#if defined(UBRR2H)
-  ring_buffer rx_buffer2  =  { { 0 }, 0, 0 };
-  ring_buffer tx_buffer2  =  { { 0 }, 0, 0 };
-#endif
-#if defined(UBRR3H)
-  ring_buffer rx_buffer3  =  { { 0 }, 0, 0 };
-  ring_buffer tx_buffer3  =  { { 0 }, 0, 0 };
-#endif
-
-inline void store_char(unsigned char c, ring_buffer *buffer)
-{
-  int i = (unsigned int)(buffer->head + 1) % SERIAL_BUFFER_SIZE;
+  int i = (unsigned int)(s->_rx_buffer_head + 1) % SERIAL_BUFFER_SIZE;
 
   // if we should be storing the received character into the location
   // just before the tail (meaning that the head would advance to the
   // current location of the tail), we're about to overflow the buffer
   // and so we don't write the character or advance the head.
-  if (i != buffer->tail) {
-    buffer->buffer[buffer->head] = c;
-    buffer->head = i;
+  if (i != s->_rx_buffer_tail) {
+    s->_rx_buffer[s->_rx_buffer_head] = c;
+    s->_rx_buffer_head = i;
   }
 }
 
@@ -126,7 +84,7 @@ inline void store_char(unsigned char c, ring_buffer *buffer)
   #if defined(UDR0)
     if (bit_is_clear(UCSR0A, UPE0)) {
       unsigned char c = UDR0;
-      store_char(c, &rx_buffer);
+      store_char(c, &Serial);
     } else {
       unsigned char c = UDR0;
     };
@@ -152,7 +110,7 @@ inline void store_char(unsigned char c, ring_buffer *buffer)
   {
     if (bit_is_clear(UCSR1A, UPE1)) {
       unsigned char c = UDR1;
-      store_char(c, &rx_buffer1);
+      store_char(c, &Serial1);
     } else {
       unsigned char c = UDR1;
     };
@@ -167,7 +125,7 @@ inline void store_char(unsigned char c, ring_buffer *buffer)
   {
     if (bit_is_clear(UCSR2A, UPE2)) {
       unsigned char c = UDR2;
-      store_char(c, &rx_buffer2);
+      store_char(c, &Serial2);
     } else {
       unsigned char c = UDR2;
     };
@@ -182,7 +140,7 @@ inline void store_char(unsigned char c, ring_buffer *buffer)
   {
     if (bit_is_clear(UCSR3A, UPE3)) {
       unsigned char c = UDR3;
-      store_char(c, &rx_buffer3);
+      store_char(c, &Serial3);
     } else {
       unsigned char c = UDR3;
     };
@@ -222,7 +180,7 @@ ISR(USART0_UDRE_vect)
 ISR(USART_UDRE_vect)
 #endif
 {
-  if (tx_buffer.head == tx_buffer.tail) {
+  if (Serial._tx_buffer_head == Serial._tx_buffer_tail) {
 	// Buffer empty, so disable interrupts
 #if defined(UCSR0B)
     cbi(UCSR0B, UDRIE0);
@@ -232,8 +190,8 @@ ISR(USART_UDRE_vect)
   }
   else {
     // There is more data in the output buffer. Send the next byte
-    unsigned char c = tx_buffer.buffer[tx_buffer.tail];
-    tx_buffer.tail = (tx_buffer.tail + 1) % SERIAL_BUFFER_SIZE;
+    unsigned char c = Serial._tx_buffer[Serial._tx_buffer_tail];
+    Serial._tx_buffer_tail = (Serial._tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
 	
   #if defined(UDR0)
     UDR0 = c;
@@ -250,14 +208,14 @@ ISR(USART_UDRE_vect)
 #ifdef USART1_UDRE_vect
 ISR(USART1_UDRE_vect)
 {
-  if (tx_buffer1.head == tx_buffer1.tail) {
+  if (Serial1._tx_buffer_head == Serial1._tx_buffer_tail) {
 	// Buffer empty, so disable interrupts
     cbi(UCSR1B, UDRIE1);
   }
   else {
     // There is more data in the output buffer. Send the next byte
-    unsigned char c = tx_buffer1.buffer[tx_buffer1.tail];
-    tx_buffer1.tail = (tx_buffer1.tail + 1) % SERIAL_BUFFER_SIZE;
+    unsigned char c = Serial1._tx_buffer[Serial1._tx_buffer_tail];
+    Serial1._tx_buffer_tail = (Serial1._tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
 	
     UDR1 = c;
   }
@@ -267,14 +225,14 @@ ISR(USART1_UDRE_vect)
 #ifdef USART2_UDRE_vect
 ISR(USART2_UDRE_vect)
 {
-  if (tx_buffer2.head == tx_buffer2.tail) {
+  if (Serial2._tx_buffer_head == Serial2._tx_buffer_tail) {
 	// Buffer empty, so disable interrupts
     cbi(UCSR2B, UDRIE2);
   }
   else {
     // There is more data in the output buffer. Send the next byte
-    unsigned char c = tx_buffer2.buffer[tx_buffer2.tail];
-    tx_buffer2.tail = (tx_buffer2.tail + 1) % SERIAL_BUFFER_SIZE;
+    unsigned char c = Serial2._tx_buffer[Serial2._tx_buffer_tail];
+    Serial2._tx_buffer_tail = (Serial2._tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
 	
     UDR2 = c;
   }
@@ -284,31 +242,30 @@ ISR(USART2_UDRE_vect)
 #ifdef USART3_UDRE_vect
 ISR(USART3_UDRE_vect)
 {
-  if (tx_buffer3.head == tx_buffer3.tail) {
+  if (Serial3._tx_buffer_head == Serial3._tx_buffer_tail) {
 	// Buffer empty, so disable interrupts
     cbi(UCSR3B, UDRIE3);
   }
   else {
     // There is more data in the output buffer. Send the next byte
-    unsigned char c = tx_buffer3.buffer[tx_buffer3.tail];
-    tx_buffer3.tail = (tx_buffer3.tail + 1) % SERIAL_BUFFER_SIZE;
+    unsigned char c = Serial3._tx_buffer[Serial3._tx_buffer_tail];
+    Serial3._tx_buffer_tail = (Serial3._tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
 	
     UDR3 = c;
   }
 }
 #endif
 
-
 // Constructors ////////////////////////////////////////////////////////////////
 
-HardwareSerial::HardwareSerial(ring_buffer *rx_buffer, ring_buffer *tx_buffer,
+HardwareSerial::HardwareSerial(
   volatile uint8_t *ubrrh, volatile uint8_t *ubrrl,
   volatile uint8_t *ucsra, volatile uint8_t *ucsrb,
   volatile uint8_t *ucsrc, volatile uint8_t *udr,
   uint8_t rxen, uint8_t txen, uint8_t rxcie, uint8_t udrie, uint8_t u2x)
 {
-  _rx_buffer = rx_buffer;
-  _tx_buffer = tx_buffer;
+  _tx_buffer_head = _tx_buffer_tail = 0;
+  _rx_buffer_head = _rx_buffer_tail = 0;
   _ubrrh = ubrrh;
   _ubrrl = ubrrl;
   _ucsra = ucsra;
@@ -416,7 +373,7 @@ try_again:
 void HardwareSerial::end()
 {
   // wait for transmission of outgoing data
-  while (_tx_buffer->head != _tx_buffer->tail)
+  while (_tx_buffer_head != _tx_buffer_tail)
     ;
 
   cbi(*_ucsrb, _rxen);
@@ -425,31 +382,31 @@ void HardwareSerial::end()
   cbi(*_ucsrb, _udrie);
   
   // clear any received data
-  _rx_buffer->head = _rx_buffer->tail;
+  _rx_buffer_head = _rx_buffer_tail;
 }
 
 int HardwareSerial::available(void)
 {
-  return (unsigned int)(SERIAL_BUFFER_SIZE + _rx_buffer->head - _rx_buffer->tail) % SERIAL_BUFFER_SIZE;
+  return (unsigned int)(SERIAL_BUFFER_SIZE + _rx_buffer_head - _rx_buffer_tail) % SERIAL_BUFFER_SIZE;
 }
 
 int HardwareSerial::peek(void)
 {
-  if (_rx_buffer->head == _rx_buffer->tail) {
+  if (_rx_buffer_head == _rx_buffer_tail) {
     return -1;
   } else {
-    return _rx_buffer->buffer[_rx_buffer->tail];
+    return _rx_buffer[_rx_buffer_tail];
   }
 }
 
 int HardwareSerial::read(void)
 {
   // if the head isn't ahead of the tail, we don't have any characters
-  if (_rx_buffer->head == _rx_buffer->tail) {
+  if (_rx_buffer_head == _rx_buffer_tail) {
     return -1;
   } else {
-    unsigned char c = _rx_buffer->buffer[_rx_buffer->tail];
-    _rx_buffer->tail = (unsigned int)(_rx_buffer->tail + 1) % SERIAL_BUFFER_SIZE;
+    unsigned char c = _rx_buffer[_rx_buffer_tail];
+    _rx_buffer_tail = (unsigned int)(_rx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
     return c;
   }
 }
@@ -463,16 +420,16 @@ void HardwareSerial::flush()
 
 size_t HardwareSerial::write(uint8_t c)
 {
-  int i = (_tx_buffer->head + 1) % SERIAL_BUFFER_SIZE;
+  int i = (_tx_buffer_head + 1) % SERIAL_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
   // ???: return 0 here instead?
-  while (i == _tx_buffer->tail)
+  while (i == _tx_buffer_tail)
     ;
 	
-  _tx_buffer->buffer[_tx_buffer->head] = c;
-  _tx_buffer->head = i;
+  _tx_buffer[_tx_buffer_head] = c;
+  _tx_buffer_head = i;
 	
   sbi(*_ucsrb, _udrie);
   // clear the TXC bit -- "can be cleared by writing a one to its bit location"
@@ -489,9 +446,9 @@ HardwareSerial::operator bool() {
 // Preinstantiate Objects //////////////////////////////////////////////////////
 
 #if defined(UBRRH) && defined(UBRRL)
-  HardwareSerial Serial(&rx_buffer, &tx_buffer, &UBRRH, &UBRRL, &UCSRA, &UCSRB, &UCSRC, &UDR, RXEN, TXEN, RXCIE, UDRIE, U2X);
+  HardwareSerial Serial(&UBRRH, &UBRRL, &UCSRA, &UCSRB, &UCSRC, &UDR, RXEN, TXEN, RXCIE, UDRIE, U2X);
 #elif defined(UBRR0H) && defined(UBRR0L)
-  HardwareSerial Serial(&rx_buffer, &tx_buffer, &UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UCSR0C, &UDR0, RXEN0, TXEN0, RXCIE0, UDRIE0, U2X0);
+  HardwareSerial Serial(&UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UCSR0C, &UDR0, RXEN0, TXEN0, RXCIE0, UDRIE0, U2X0);
 #elif defined(USBCON)
   // do nothing - Serial object and buffers are initialized in CDC code
 #else
@@ -499,13 +456,13 @@ HardwareSerial::operator bool() {
 #endif
 
 #if defined(UBRR1H)
-  HardwareSerial Serial1(&rx_buffer1, &tx_buffer1, &UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UCSR1C, &UDR1, RXEN1, TXEN1, RXCIE1, UDRIE1, U2X1);
+  HardwareSerial Serial1(&UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UCSR1C, &UDR1, RXEN1, TXEN1, RXCIE1, UDRIE1, U2X1);
 #endif
 #if defined(UBRR2H)
-  HardwareSerial Serial2(&rx_buffer2, &tx_buffer2, &UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UCSR2C, &UDR2, RXEN2, TXEN2, RXCIE2, UDRIE2, U2X2);
+  HardwareSerial Serial2(&UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UCSR2C, &UDR2, RXEN2, TXEN2, RXCIE2, UDRIE2, U2X2);
 #endif
 #if defined(UBRR3H)
-  HardwareSerial Serial3(&rx_buffer3, &tx_buffer3, &UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UCSR3C, &UDR3, RXEN3, TXEN3, RXCIE3, UDRIE3, U2X3);
+  HardwareSerial Serial3(&UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UCSR3C, &UDR3, RXEN3, TXEN3, RXCIE3, UDRIE3, U2X3);
 #endif
 
 #endif // whole file
diff --git a/cores/arduino/HardwareSerial.h b/cores/arduino/HardwareSerial.h
index a73117f..a091e03 100644
--- a/cores/arduino/HardwareSerial.h
+++ b/cores/arduino/HardwareSerial.h
@@ -27,13 +27,19 @@
 
 #include "Stream.h"
 
-struct ring_buffer;
+// Define constants and variables for buffering incoming serial data.  We're
+// 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 (RAMEND < 1000)
+  #define SERIAL_BUFFER_SIZE 16
+#else
+  #define SERIAL_BUFFER_SIZE 64
+#endif
 
 class HardwareSerial : public Stream
 {
   private:
-    ring_buffer *_rx_buffer;
-    ring_buffer *_tx_buffer;
     volatile uint8_t *_ubrrh;
     volatile uint8_t *_ubrrl;
     volatile uint8_t *_ucsra;
@@ -46,8 +52,20 @@ class HardwareSerial : public Stream
     uint8_t _udrie;
     uint8_t _u2x;
     bool transmitting;
+
   public:
-    HardwareSerial(ring_buffer *rx_buffer, ring_buffer *tx_buffer,
+    volatile uint8_t _rx_buffer_head;
+    volatile uint8_t _rx_buffer_tail;
+    volatile uint8_t _tx_buffer_head;
+    volatile uint8_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
+    // instruction.
+    unsigned char _rx_buffer[SERIAL_BUFFER_SIZE];
+    unsigned char _tx_buffer[SERIAL_BUFFER_SIZE];
+
+    HardwareSerial(
       volatile uint8_t *ubrrh, volatile uint8_t *ubrrl,
       volatile uint8_t *ucsra, volatile uint8_t *ucsrb,
       volatile uint8_t *ucsrc, volatile uint8_t *udr,