diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index ce1bb57db17f..55fd5474b210 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -171,6 +171,7 @@ struct mount {
 #define	MNT_NOSYMFOLLOW	0x00400000	/* do not follow symlinks */
 #define	MNT_JAILDEVFS	0x02000000	/* Jail friendly DEVFS behaviour */
 #define	MNT_MULTILABEL	0x04000000	/* MAC support for individual objects */
+#define	MNT_ACLS	0x08000000	/* ACL support enabled */
 #define	MNT_NOATIME	0x10000000	/* disable update of file access time */
 #define	MNT_NOCLUSTERR	0x40000000	/* disable cluster read */
 #define	MNT_NOCLUSTERW	0x80000000	/* disable cluster write */
@@ -209,15 +210,14 @@ struct mount {
 			MNT_ROOTFS	| MNT_NOATIME	| MNT_NOCLUSTERR| \
 			MNT_NOCLUSTERW	| MNT_SUIDDIR	| MNT_SOFTDEP	| \
 			MNT_IGNORE	| MNT_EXPUBLIC	| MNT_NOSYMFOLLOW | \
-			MNT_JAILDEVFS	| MNT_MULTILABEL)
+			MNT_JAILDEVFS	| MNT_MULTILABEL | MNT_ACLS)
 
 /* Mask of flags that can be updated */
 #define MNT_UPDATEMASK (MNT_NOSUID	| MNT_NOEXEC	| MNT_NODEV	| \
 			MNT_SYNCHRONOUS	| MNT_UNION	| MNT_ASYNC	| \
 			MNT_NOATIME | \
 			MNT_NOSYMFOLLOW	| MNT_IGNORE	| MNT_JAILDEVFS	| \
-			MNT_NOCLUSTERR	| MNT_NOCLUSTERW | MNT_SUIDDIR | \
-			MNT_MULTILABEL)
+			MNT_NOCLUSTERR	| MNT_NOCLUSTERW | MNT_SUIDDIR)
   
 /*
  * External filesystem command modifier flags.