diff --git a/exfat/mkfs/cbm.c b/exfat/mkfs/cbm.c
new file mode 100644
index 0000000..6d948b4
--- /dev/null
+++ b/exfat/mkfs/cbm.c
@@ -0,0 +1,74 @@
+/*
+	cbm.c (09.11.10)
+	Clusters Bitmap creation code.
+
+	Copyright (C) 2011, 2012  Andrew Nayenko
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <limits.h>
+#include "cbm.h"
+#include "fat.h"
+#include "uct.h"
+#include "rootdir.h"
+
+static off64_t cbm_alignment(void)
+{
+	return get_cluster_size();
+}
+
+static off64_t cbm_size(void)
+{
+	return DIV_ROUND_UP(
+			(get_volume_size() - get_position(&cbm)) / get_cluster_size(),
+			CHAR_BIT);
+}
+
+static int cbm_write(struct exfat_dev* dev)
+{
+	uint32_t allocated_clusters =
+			DIV_ROUND_UP(cbm.get_size(), get_cluster_size()) +
+			DIV_ROUND_UP(uct.get_size(), get_cluster_size()) +
+			DIV_ROUND_UP(rootdir.get_size(), get_cluster_size());
+	size_t bitmap_size = DIV_ROUND_UP(allocated_clusters, CHAR_BIT);
+	uint8_t* bitmap = malloc(bitmap_size);
+	size_t i;
+
+	if (bitmap == NULL)
+	{
+		exfat_error("failed to allocate bitmap of %zu bytes", bitmap_size);
+		return 1;
+	}
+
+	for (i = 0; i < bitmap_size * CHAR_BIT; i++)
+		if (i < allocated_clusters)
+			BMAP_SET(bitmap, i);
+		else
+			BMAP_CLR(bitmap, i);
+	if (exfat_write(dev, bitmap, bitmap_size) < 0)
+	{
+		exfat_error("failed to write bitmap of %zu bytes", bitmap_size);
+		return 1;
+	}
+	free(bitmap);
+	return 0;
+}
+
+const struct fs_object cbm =
+{
+	.get_alignment = cbm_alignment,
+	.get_size = cbm_size,
+	.write = cbm_write,
+};