diff --git a/UART.h b/UART.h
index 1d8328a..02b2f82 100644
--- a/UART.h
+++ b/UART.h
@@ -9,6 +9,7 @@
 #define UART_UART_H_
 
 #include "stdio.h"
+#include "string.h"
 
 void UART_char(unsigned char c);
 void UART_int(unsigned int);