diff --git a/avr_usart.h b/avr_usart.h
index af1865a..881f287 100644
--- a/avr_usart.h
+++ b/avr_usart.h
@@ -5,7 +5,7 @@
  * Filename: avr_at-09.h
  */
 
-#include <avr/inttypes.h>
+#include <inttypes.h>
 
 //#############################
 //PIN DEFINES AND CONSTS
@@ -46,8 +46,8 @@ void init_usart0(void);
 void tx_usart0(unsigned char data);
 unsigned char rx_usart0(void);
 
-void serial0_write(char* buffer, uint8_t write_length);
-void serial0_read(char* buffer, uint8_t buf_length);
+void serial0_write(unsigned char* buffer, uint8_t write_length);
+void serial0_read(unsigned char* buffer, uint8_t buf_length);
 void serial0_set_baud(uint8_t baud);
 void seiral0_enable_timeouts(uint8_t ms);