diff --git a/cores/arduino/WInterrupts.c b/cores/arduino/WInterrupts.c
index de49cd1..d3fbf10 100644
--- a/cores/arduino/WInterrupts.c
+++ b/cores/arduino/WInterrupts.c
@@ -51,14 +51,14 @@ void attachInterrupt(uint8_t interruptNum, void (*userFunc)(void), int mode) {
 	// I hate doing this, but the register assignment differs between the 1280/2560
 	// and the 32U4.  Since avrlib defines registers PCMSK1 and PCMSK2 that aren't 
 	// even present on the 32U4 this is the only way to distinguish between them.
-	case 0:
-		EICRA = (EICRA & ~((1<<ISC00) | (1<<ISC01))) | (mode << ISC00);
-		EIMSK |= (1<<INT0);
-		break;
-	case 1:
-		EICRA = (EICRA & ~((1<<ISC10) | (1<<ISC11))) | (mode << ISC10);
-		EIMSK |= (1<<INT1);
-		break;	
+    case 0:
+	EICRA = (EICRA & ~((1<<ISC00) | (1<<ISC01))) | (mode << ISC00);
+	EIMSK |= (1<<INT0);
+	break;
+    case 1:
+	EICRA = (EICRA & ~((1<<ISC10) | (1<<ISC11))) | (mode << ISC10);
+	EIMSK |= (1<<INT1);
+	break;	
     case 2:
         EICRA = (EICRA & ~((1<<ISC20) | (1<<ISC21))) | (mode << ISC20);
         EIMSK |= (1<<INT2);
@@ -67,6 +67,10 @@ void attachInterrupt(uint8_t interruptNum, void (*userFunc)(void), int mode) {
         EICRA = (EICRA & ~((1<<ISC30) | (1<<ISC31))) | (mode << ISC30);
         EIMSK |= (1<<INT3);
         break;
+    case 4:
+        EICRB = (EICRB & ~((1<<ISC60) | (1<<ISC61))) | (mode << ISC60);
+        EIMSK |= (1<<INT6);
+        break;
 #elif defined(EICRA) && defined(EICRB) && defined(EIMSK)
     case 2:
       EICRA = (EICRA & ~((1 << ISC00) | (1 << ISC01))) | (mode << ISC00);
@@ -166,7 +170,10 @@ void detachInterrupt(uint8_t interruptNum) {
         break;
     case 3:
         EIMSK &= ~(1<<INT3);
-        break;		
+        break;	
+    case 4:
+        EIMSK &= ~(1<<INT6);
+        break;	
 #elif defined(EICRA) && defined(EICRB) && defined(EIMSK)
     case 2:
       EIMSK &= ~(1 << INT0);
@@ -250,6 +257,11 @@ ISR(INT3_vect) {
 		intFunc[EXTERNAL_INT_3]();
 }
 
+ISR(INT6_vect) {
+    if(intFunc[EXTERNAL_INT_4])
+		intFunc[EXTERNAL_INT_4]();
+}
+
 #elif defined(EICRA) && defined(EICRB)
 
 ISR(INT0_vect) {
diff --git a/cores/arduino/wiring_private.h b/cores/arduino/wiring_private.h
index 90dbf2c..c366005 100755
--- a/cores/arduino/wiring_private.h
+++ b/cores/arduino/wiring_private.h
@@ -57,7 +57,7 @@ extern "C"{
 #elif defined(__AVR_ATmega1284__) || defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega644__) || defined(__AVR_ATmega644A__) || defined(__AVR_ATmega644P__) || defined(__AVR_ATmega644PA__)
 #define EXTERNAL_NUM_INTERRUPTS 3
 #elif defined(__AVR_ATmega32U4__)
-#define EXTERNAL_NUM_INTERRUPTS 4
+#define EXTERNAL_NUM_INTERRUPTS 5
 #else
 #define EXTERNAL_NUM_INTERRUPTS 2
 #endif