diff --git a/nova/tests/unit/virt/libvirt/volume/test_net.py b/nova/tests/unit/virt/libvirt/volume/test_net.py
index 640c1709ded8..29dfb6268f0a 100644
--- a/nova/tests/unit/virt/libvirt/volume/test_net.py
+++ b/nova/tests/unit/virt/libvirt/volume/test_net.py
@@ -150,7 +150,8 @@ class LibvirtNetVolumeDriverTestCase(
         secret_uuid wasn't set on the cinder side for the original connection
         which is now persisted in the
         nova.block_device_mappings.connection_info column and used here. In
-        this case we fallback to use the local config for secret_uuid.
+        this case we fallback to use the local config for secret_uuid and
+        username.
         """
         libvirt_driver = net.LibvirtNetVolumeDriver(self.fake_host)
         connection_info = self.rbd_connection(self.vol)
@@ -170,7 +171,7 @@ class LibvirtNetVolumeDriverTestCase(
         conf = libvirt_driver.get_config(connection_info, self.disk_info)
         tree = conf.format_dom()
         self._assertNetworkAndProtocolEquals(tree)
-        self.assertEqual(self.user, tree.find('./auth').get('username'))
+        self.assertEqual(flags_user, tree.find('./auth').get('username'))
         self.assertEqual(secret_type, tree.find('./auth/secret').get('type'))
         # Assert that the secret_uuid comes from CONF.libvirt.rbd_secret_uuid.
         self.assertEqual(flags_uuid, tree.find('./auth/secret').get('uuid'))
diff --git a/nova/virt/libvirt/volume/net.py b/nova/virt/libvirt/volume/net.py
index 3b432dea54c1..e420415a2cf6 100644
--- a/nova/virt/libvirt/volume/net.py
+++ b/nova/virt/libvirt/volume/net.py
@@ -69,8 +69,11 @@ class LibvirtNetVolumeDriver(libvirt_volume.LibvirtBaseVolumeDriver):
             if netdisk_properties['secret_uuid'] is not None:
                 conf.auth_secret_uuid = netdisk_properties['secret_uuid']
             else:
+                # If we're using the rbd_secret_uuid from nova.conf we need to
+                # use the rbd_user from nova.conf as well.
                 LOG.debug('Falling back to Nova configuration for RBD auth '
-                          'secret_uuid value.')
+                          'secret_uuid and username values.')
+                conf.auth_username = CONF.libvirt.rbd_user
                 conf.auth_secret_uuid = CONF.libvirt.rbd_secret_uuid
             # secret_type is always hard-coded to 'ceph' in cinder
             conf.auth_secret_type = netdisk_properties['secret_type']