diff --git a/tests/qemu-iotests/304 b/tests/qemu-iotests/304
new file mode 100755
index 0000000000..aaf9e14617
--- /dev/null
+++ b/tests/qemu-iotests/304
@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+#
+# Tests dirty-bitmap backup with unaligned bitmap granularity
+#
+# Copyright (c) 2020 Proxmox Server Solutions
+#
+# 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 2 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/>.
+#
+# owner=s.reiter@proxmox.com
+
+import iotests
+from iotests import qemu_img_create, qemu_img_log, file_path
+
+iotests.script_initialize(supported_fmts=['qcow2'],
+                          supported_protocols=['file'])
+
+test_img = file_path('test.qcow2')
+target_img = file_path('target.qcow2')
+
+# unaligned by one byte
+image_len = 4097
+bitmap_granularity = 4096
+
+qemu_img_create('-f', iotests.imgfmt, test_img, str(image_len))
+
+# create VM
+vm = iotests.VM().add_drive(test_img)
+vm.launch()
+
+# write to the entire image
+vm.hmp_qemu_io('drive0', 'write -P0x16 0 4096');
+vm.hmp_qemu_io('drive0', 'write -P0x17 4096 1');
+
+# do backup and wait for completion
+vm.qmp('drive-backup', **{
+    'device': 'drive0',
+    'sync': 'full',
+    'target': target_img
+})
+
+event = vm.event_wait(name='BLOCK_JOB_COMPLETED',
+                      match={'data': {'device': 'drive0'}},
+                      timeout=5.0)
+
+# shutdown to sync images
+vm.shutdown()
+
+# backup succeeded, check if image is correct
+qemu_img_log('compare', test_img, target_img)
diff --git a/tests/qemu-iotests/304.out b/tests/qemu-iotests/304.out
new file mode 100644
index 0000000000..381cc056f7
--- /dev/null
+++ b/tests/qemu-iotests/304.out
@@ -0,0 +1,2 @@
+Images are identical.
+
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 025ed5238d..7f76066640 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -309,3 +309,4 @@
 299 auto quick
 301 backing quick
 302 quick
+304 rw quick