diff --git a/sys/kern/subr_devstat.c b/sys/kern/subr_devstat.c
--- a/sys/kern/subr_devstat.c
+++ b/sys/kern/subr_devstat.c
@@ -209,7 +209,8 @@
 	 * Keep a count of the various tag types sent.
 	 */
 	if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
-	    tag_type != DEVSTAT_TAG_NONE)
+	    tag_type >= DEVSTAT_TAG_SIMPLE &&
+	    tag_type < (devstat_tag_type)nitems(ds->tag_types))
 		ds->tag_types[tag_type]++;
 
 	/*