diff --git a/utf8.c b/utf8.c
index c555ecda..e9803d7a 100644
--- a/utf8.c
+++ b/utf8.c
@@ -134,6 +134,8 @@ utf8_from_data(const struct utf8_data *ud, utf8_char *uc)
 	union utf8_map	 m = { .uc = 0 };
 	u_int		 offset;
 
+	if (ud->width == 0)
+		goto fail;
 	if (ud->width != 1 && ud->width != 2)
 		fatalx("invalid UTF-8 width");
 	if (ud->size == 0)