diff --git a/zaza/openstack/configure/guest.py b/zaza/openstack/configure/guest.py
index 9a92541..797ce28 100644
--- a/zaza/openstack/configure/guest.py
+++ b/zaza/openstack/configure/guest.py
@@ -130,7 +130,7 @@ def launch_instance(instance_key, use_boot_volume=False, vm_name=None,
     :param host: Requested host to create servers
     :type host: str
     :param nova_api_version: Nova API version to use
-    :type nova_api_version: str
+    :type nova_api_version: str | None
     :returns: the created instance
     :rtype: novaclient.Server
     """
diff --git a/zaza/openstack/utilities/openstack.py b/zaza/openstack/utilities/openstack.py
index ec6cee4..3875aff 100644
--- a/zaza/openstack/utilities/openstack.py
+++ b/zaza/openstack/utilities/openstack.py
@@ -373,7 +373,7 @@ def get_nova_session_client(session, version=None):
     :param session: Keystone session object
     :type session: keystoneauth1.session.Session object
     :param version: Version of client to request.
-    :type version: float
+    :type version: float | str | None
     :returns: Authenticated novaclient
     :rtype: novaclient.Client object
     """