diff --git a/utf8.c b/utf8.c
index f93891a6..10ccf422 100644
--- a/utf8.c
+++ b/utf8.c
@@ -72,7 +72,7 @@ static u_int utf8_next_index;
 
 /* Get a UTF-8 item from data. */
 static struct utf8_item *
-utf8_item_by_data(const char *data, size_t size)
+utf8_item_by_data(const u_char *data, size_t size)
 {
 	struct utf8_item	ui;