diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp
index d96b47f..ed29641 100644
--- a/cores/arduino/HardwareSerial.cpp
+++ b/cores/arduino/HardwareSerial.cpp
@@ -117,7 +117,7 @@ void HardwareSerial::begin(unsigned long baud, byte config)
     baud_setting = (F_CPU / 8 / baud - 1) / 2;
   }
 
-  // assign the baud_setting, a.k.a. ubbr (USART Baud Rate Register)
+  // assign the baud_setting, a.k.a. ubrr (USART Baud Rate Register)
   *_ubrrh = baud_setting >> 8;
   *_ubrrl = baud_setting;
 
diff --git a/cores/arduino/HardwareSerial0.cpp b/cores/arduino/HardwareSerial0.cpp
index 67495ad..1146eeb 100644
--- a/cores/arduino/HardwareSerial0.cpp
+++ b/cores/arduino/HardwareSerial0.cpp
@@ -43,7 +43,7 @@
 #elif defined(USART_RXC_vect)
   ISR(USART_RXC_vect) // ATmega8
 #else
-  #error "Don't know what the Data Received vector is called for the first UART"
+  #error "Don't know what the Data Received vector is called for Serial"
 #endif
   {
     Serial._rx_complete_irq();
@@ -58,7 +58,7 @@ ISR(USART0_UDRE_vect)
 #elif defined(USART_UDRE_vect)
 ISR(USART_UDRE_vect)
 #else
-  #error "Don't know what the Data Register Empty vector is called for the first UART"
+  #error "Don't know what the Data Register Empty vector is called for Serial"
 #endif
 {
   Serial._tx_udr_empty_irq();
diff --git a/cores/arduino/HardwareSerial1.cpp b/cores/arduino/HardwareSerial1.cpp
index ec076e7..19625e2 100644
--- a/cores/arduino/HardwareSerial1.cpp
+++ b/cores/arduino/HardwareSerial1.cpp
@@ -36,39 +36,29 @@
 
 #if defined(HAVE_HWSERIAL1)
 
-#if defined(USART_RX_vect)
-  ISR(USART_RX_vect)
+#if defined(UART1_RX_vect)
+ISR(UART1_RX_vect)
 #elif defined(USART1_RX_vect)
-  ISR(USART1_RX_vect)
-#elif defined(USART_RXC_vect)
-  ISR(USART_RXC_vect) // ATmega8
+ISR(USART1_RX_vect)
 #else
-  #error "Don't know what the Data Received vector is called for the first UART"
+#error "Don't know what the Data Register Empty vector is called for Serial1"
 #endif
-  {
-    Serial1._rx_complete_irq();
-  }
+{
+  Serial1._rx_complete_irq();
+}
 
 #if defined(UART1_UDRE_vect)
 ISR(UART1_UDRE_vect)
-#elif defined(UART_UDRE_vect)
-ISR(UART_UDRE_vect)
 #elif defined(USART1_UDRE_vect)
 ISR(USART1_UDRE_vect)
-#elif defined(USART_UDRE_vect)
-ISR(USART_UDRE_vect)
 #else
-  #error "Don't know what the Data Register Empty vector is called for the first UART"
+#error "Don't know what the Data Register Empty vector is called for Serial1"
 #endif
 {
   Serial1._tx_udr_empty_irq();
 }
 
-#if defined(UBRRH) && defined(UBRRL)
-  HardwareSerial Serial1(&UBRRH, &UBRRL, &UCSRA, &UCSRB, &UCSRC, &UDR);
-#else
-  HardwareSerial Serial1(&UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UCSR1C, &UDR1);
-#endif
+HardwareSerial Serial1(&UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UCSR1C, &UDR1);
 
 // Function that can be weakly referenced by serialEventRun to prevent
 // pulling in this file if it's not otherwise used.
diff --git a/cores/arduino/HardwareSerial2.cpp b/cores/arduino/HardwareSerial2.cpp
index e700770..fd334ae 100644
--- a/cores/arduino/HardwareSerial2.cpp
+++ b/cores/arduino/HardwareSerial2.cpp
@@ -36,39 +36,17 @@
 
 #if defined(HAVE_HWSERIAL2)
 
-#if defined(USART_RX_vect)
-  ISR(USART_RX_vect)
-#elif defined(USART2_RX_vect)
-  ISR(USART2_RX_vect)
-#elif defined(USART_RXC_vect)
-  ISR(USART_RXC_vect) // ATmega8
-#else
-  #error "Don't know what the Data Received vector is called for the first UART"
-#endif
-  {
-    Serial2._rx_complete_irq();
-  }
+ISR(USART2_RX_vect)
+{
+  Serial2._rx_complete_irq();
+}
 
-#if defined(UART2_UDRE_vect)
-ISR(UART2_UDRE_vect)
-#elif defined(UART_UDRE_vect)
-ISR(UART_UDRE_vect)
-#elif defined(USART2_UDRE_vect)
 ISR(USART2_UDRE_vect)
-#elif defined(USART_UDRE_vect)
-ISR(USART_UDRE_vect)
-#else
-  #error "Don't know what the Data Register Empty vector is called for the first UART"
-#endif
 {
   Serial2._tx_udr_empty_irq();
 }
 
-#if defined(UBRRH) && defined(UBRRL)
-  HardwareSerial Serial2(&UBRRH, &UBRRL, &UCSRA, &UCSRB, &UCSRC, &UDR);
-#else
-  HardwareSerial Serial2(&UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UCSR2C, &UDR2);
-#endif
+HardwareSerial Serial2(&UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UCSR2C, &UDR2);
 
 // Function that can be weakly referenced by serialEventRun to prevent
 // pulling in this file if it's not otherwise used.
diff --git a/cores/arduino/HardwareSerial3.cpp b/cores/arduino/HardwareSerial3.cpp
index 300c4bd..a68095b 100644
--- a/cores/arduino/HardwareSerial3.cpp
+++ b/cores/arduino/HardwareSerial3.cpp
@@ -36,39 +36,17 @@
 
 #if defined(HAVE_HWSERIAL3)
 
-#if defined(USART_RX_vect)
-  ISR(USART_RX_vect)
-#elif defined(USART3_RX_vect)
-  ISR(USART3_RX_vect)
-#elif defined(USART_RXC_vect)
-  ISR(USART_RXC_vect) // ATmega8
-#else
-  #error "Don't know what the Data Received vector is called for the first UART"
-#endif
-  {
-    Serial3._rx_complete_irq();
-  }
+ISR(USART3_RX_vect)
+{
+  Serial3._rx_complete_irq();
+}
 
-#if defined(UART3_UDRE_vect)
-ISR(UART3_UDRE_vect)
-#elif defined(UART_UDRE_vect)
-ISR(UART_UDRE_vect)
-#elif defined(USART3_UDRE_vect)
 ISR(USART3_UDRE_vect)
-#elif defined(USART_UDRE_vect)
-ISR(USART_UDRE_vect)
-#else
-  #error "Don't know what the Data Register Empty vector is called for the first UART"
-#endif
 {
   Serial3._tx_udr_empty_irq();
 }
 
-#if defined(UBRRH) && defined(UBRRL)
-  HardwareSerial Serial3(&UBRRH, &UBRRL, &UCSRA, &UCSRB, &UCSRC, &UDR);
-#else
-  HardwareSerial Serial3(&UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UCSR3C, &UDR3);
-#endif
+HardwareSerial Serial3(&UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UCSR3C, &UDR3);
 
 // Function that can be weakly referenced by serialEventRun to prevent
 // pulling in this file if it's not otherwise used.