diff --git a/sys/fs/tmpfs/tmpfs_vfsops.c b/sys/fs/tmpfs/tmpfs_vfsops.c
index fee923e6132..bb2ae154af9 100644
--- a/sys/fs/tmpfs/tmpfs_vfsops.c
+++ b/sys/fs/tmpfs/tmpfs_vfsops.c
@@ -372,6 +372,13 @@ tmpfs_mount(struct mount *mp)
 		}
 		tmp->tm_nomtime = vfs_getopt(mp->mnt_optnew, "nomtime", NULL,
 		    0) == 0;
+		MNT_ILOCK(mp);
+		if ((mp->mnt_flag & MNT_UNION) == 0) {
+			mp->mnt_kern_flag |= MNTK_FPLOOKUP;
+		} else {
+			mp->mnt_kern_flag &= ~MNTK_FPLOOKUP;
+		}
+		MNT_IUNLOCK(mp);
 		return (0);
 	}
 
@@ -462,7 +469,7 @@ tmpfs_mount(struct mount *mp)
 	mp->mnt_flag |= MNT_LOCAL;
 	mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED |
 	    MNTK_TEXT_REFS | MNTK_NOMSYNC;
-	if (!nonc)
+	if (!nonc && (mp->mnt_flag & MNT_UNION) == 0)
 		mp->mnt_kern_flag |= MNTK_FPLOOKUP;
 	MNT_IUNLOCK(mp);
 
diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
index e6718a9994f..7d4e721fb76 100644
--- a/sys/kern/vfs_cache.c
+++ b/sys/kern/vfs_cache.c
@@ -3701,8 +3701,6 @@ cache_fplookup_mp_supported(struct mount *mp)
 		return (false);
 	if ((mp->mnt_kern_flag & MNTK_FPLOOKUP) == 0)
 		return (false);
-	if ((mp->mnt_flag & MNT_UNION) != 0)
-		return (false);
 	return (true);
 }
 
diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index 8c69212d82e..834930b5e99 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -805,7 +805,7 @@ ffs_mount(struct mount *mp)
 	 */
 	if ((mp->mnt_kern_flag & MNTK_FPLOOKUP) != 0)
 		panic("MNTK_FPLOOKUP set on mount %p when it should not be", mp);
-	if ((mp->mnt_flag & (MNT_ACLS | MNT_NFS4ACLS)) == 0)
+	if ((mp->mnt_flag & (MNT_ACLS | MNT_NFS4ACLS | MNT_UNION)) == 0)
 		mp->mnt_kern_flag |= MNTK_FPLOOKUP;
 	MNT_IUNLOCK(mp);