diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 119bb6dd5ce..8509a6ce49a 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -344,7 +344,7 @@ struct mbuf {
  */
 #define	EXT_CLUSTER	1	/* mbuf cluster */
 #define	EXT_SFBUF	2	/* sendfile(2)'s sf_bufs */
-#define	EXT_JUMBOP	3	/* jumbo cluster 4096 bytes */
+#define	EXT_JUMBOP	3	/* jumbo cluster page sized */
 #define	EXT_JUMBO9	4	/* jumbo cluster 9216 bytes */
 #define	EXT_JUMBO16	5	/* jumbo cluster 16184 bytes */
 #define	EXT_PACKET	6	/* mbuf+cluster from packet zone */