diff --git a/source/firmware/kernel/shell.c b/source/firmware/kernel/shell.c
index 1edfd13..0cfdba2 100644
--- a/source/firmware/kernel/shell.c
+++ b/source/firmware/kernel/shell.c
@@ -44,17 +44,19 @@ static void parse(const char *buffer, unsigned int len)
 
 static void rx_func(void *arg)
 {
-	char buffer[80];
+	char buffer[81];
 	unsigned int index = 0;
 	int ret = 0;
 	open(shell_object.shell_device);
 	while(1) {
 		ret = read(shell_object.shell_device, &buffer[index],
-				sizeof(buffer) / sizeof(buffer[0]) - index);
+				sizeof(buffer) / sizeof(buffer[0]) - index - 1);
 		if(ret) {
+			write(shell_object.shell_device, &buffer[index], ret);	// echo
 			if((buffer[index + ret - 1] == '\n') || (buffer[index + ret - 1] == '\r')) {
 				buffer[index + ret - 1] = '\n';
 				parse(buffer, index + ret);
+				buffer[index + ret] = '\0';
 				index = 0;
 			}
 			else