--- src/sys/vfs/hammer/hammer_vfsops.c	2008/06/20 21:24:53	1.51
+++ src/sys/vfs/hammer/hammer_vfsops.c	2008/06/23 21:42:48	1.52
@@ -249,6 +249,10 @@ hammer_vfs_mount(struct mount *mp, char
 		if (info.nvolumes <= 0 || info.nvolumes >= 32768)
 			return (EINVAL);
 	}
+	if ((info.hflags & HMNT_MASTERID) &&
+	    (info.masterid < -1 || info.masterid >= HAMMER_MAX_MASTERS)) {
+			return (EINVAL);
+	}
 
 	/*
 	 * Interal mount data structure
@@ -292,6 +296,10 @@ hammer_vfs_mount(struct mount *mp, char
 	}
 	hmp->hflags &= ~HMNT_USERFLAGS;
 	hmp->hflags |= info.hflags & HMNT_USERFLAGS;
+	if (info.hflags & HMNT_MASTERID)
+		hmp->masterid = -1;
+	else
+		hmp->masterid = info.masterid;
 	if (info.asof) {
 		kprintf("ASOF\n");
 		mp->mnt_flag |= MNT_RDONLY;