diff --git a/software/AVR8/Makefile b/software/AVR8/Makefile
index 405ebcf..6e8afdf 100644
--- a/software/AVR8/Makefile
+++ b/software/AVR8/Makefile
@@ -4,7 +4,7 @@ ISPPORT ?= /dev/ttyUSB0
 
 VERSION = 0.1
 
-HEADERS =
+HEADERS = sss7.h uart.h
 SRC = main.c sss7.c uart.c
 TARGET = sss7
 OBJDIR = bin
@@ -32,7 +32,7 @@ start:
 	@echo ":: Building for $(AVRMCU)"
 	@echo ":: MCU operating frequency is $(F_CPU)Hz"
 
-$(OBJDIR)/$(AVRMCU)/%.o : %.c $(HEADERS)
+$(OBJDIR)/$(AVRMCU)/%.o : %.c $(HEADERS) Makefile
 	@mkdir -p $$(dirname $@)
 	$(CC) $(CFLAGS) -c $< -o $@
 
diff --git a/software/AVR8/main.c b/software/AVR8/main.c
index 18fb381..df74832 100644
--- a/software/AVR8/main.c
+++ b/software/AVR8/main.c
@@ -1,6 +1,7 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <util/delay.h>
+#include <string.h>
 
 #include "uart.h"
 #include "sss7.h"
@@ -11,6 +12,7 @@
 int main(void) {
 
 uint8_t msg[SSS7_PAYLOAD_SIZE];
+memset(msg, 0, SSS7_PAYLOAD_SIZE);
 msg[0] = 'H';
 msg[1] = 'e';
 msg[2] = 'l';
@@ -23,6 +25,8 @@ msg[8] = 'r';
 msg[9] = 'l';
 msg[10] = 'd';
 
+
+
 uart_init();
 sss7_init();
 sei();
@@ -32,6 +36,10 @@ while(1) {
     if(sss7_can_send()) {
         sss7_send(msg);
     }
+    while(!sss7_can_send());
+    if(sss7_send_failed()) {
+        PORTB ^= (1 << PB2);
+    }
 
     _delay_ms(250);
 }
diff --git a/software/AVR8/sss7.c b/software/AVR8/sss7.c
index e309b05..9aaf671 100644
--- a/software/AVR8/sss7.c
+++ b/software/AVR8/sss7.c
@@ -61,12 +61,12 @@ void sss7_send(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
 
 	// Commit to send state
 	sss7_state = SSS7_TX_HEADER;
+	sss7_tx_failed = 0;
 	sss7_send_byte(SSS7_HEADER[0]);
 }
 
 
 ISR(USART_RXC_vect) {
-	PORTB ^= (1 << PB3);
 	uint8_t byte = UDR;
 	uint8_t crc = 0;
 
@@ -120,7 +120,6 @@ ISR(USART_RXC_vect) {
 }
 
 ISR(USART_TXC_vect) {
-	PORTB ^= (1 << PB2);
 
 	if(sss7_tx_last_ack) {
 		uint8_t byte;
diff --git a/software/AVR8/sss7.h b/software/AVR8/sss7.h
index f4ab3db..3347100 100644
--- a/software/AVR8/sss7.h
+++ b/software/AVR8/sss7.h
@@ -33,7 +33,7 @@ static inline uint8_t sss7_can_send(void) {
 void sss7_send(uint8_t msg[SSS7_PAYLOAD_SIZE]);
 
 static inline uint8_t sss7_send_failed(void) {
-	return sss7_state != SSS7_IDLE && sss7_tx_failed;
+	return sss7_state == SSS7_IDLE && sss7_tx_failed;
 }
 
 static inline uint8_t sss7_has_received(void) {