diff --git a/tqftpserv.c b/tqftpserv.c
index 9f7c15b..045566b 100644
--- a/tqftpserv.c
+++ b/tqftpserv.c
@@ -62,8 +62,8 @@ static ssize_t tftp_send_data(struct tftp_client *client,
 {
 	ssize_t len;
 	size_t send_len;
-	char *buf = client->blk_buf;
-	char *p = buf;
+	uint8_t *buf = client->blk_buf;
+	uint8_t *p = buf;
 
 	*p++ = 0;
 	*p++ = OP_DATA;