diff --git a/cinderclient/api_versions.py b/cinderclient/api_versions.py
index 537b77993..33ba5087d 100644
--- a/cinderclient/api_versions.py
+++ b/cinderclient/api_versions.py
@@ -29,7 +29,7 @@ LOG = logging.getLogger(__name__)
 # key is a deprecated version and value is an alternative version.
 DEPRECATED_VERSIONS = {"1": "2"}
 DEPRECATED_VERSION = "2.0"
-MAX_VERSION = "3.40"
+MAX_VERSION = "3.44"
 MIN_VERSION = "3.0"
 
 _SUBSTITUTIONS = {}
diff --git a/cinderclient/v3/attachments.py b/cinderclient/v3/attachments.py
index 1eab8b100..614662684 100644
--- a/cinderclient/v3/attachments.py
+++ b/cinderclient/v3/attachments.py
@@ -66,3 +66,20 @@ class VolumeAttachmentManager(base.ManagerWithFind):
         resp = self._update('/attachments/%s' % id, body)
         return self.resource_class(self, resp['attachment'], loaded=True,
                                    resp=resp)
+
+    def complete(self, attachment):
+        """Mark the attachment as completed."""
+        resp, body = self._action_return_resp_and_body('os-complete',
+                                                       attachment,
+                                                       None)
+        return resp
+
+    def _action_return_resp_and_body(self, action, attachment, info=None,
+                                     **kwargs):
+        """Perform a attachments "action" and return response headers and body.
+
+        """
+        body = {action: info}
+        self.run_hooks('modify_body_for_action', body, **kwargs)
+        url = '/attachments/%s/action' % base.getid(attachment)
+        return self.api.client.post(url, body=body)
diff --git a/cinderclient/v3/shell.py b/cinderclient/v3/shell.py
index 9b6f1151d..97740e4c2 100644
--- a/cinderclient/v3/shell.py
+++ b/cinderclient/v3/shell.py
@@ -1937,6 +1937,16 @@ def do_attachment_delete(cs, args):
         cs.attachments.delete(attachment)
 
 
+@api_versions.wraps('3.44')
+@utils.arg('attachment',
+           metavar='<attachment>', nargs='+',
+           help='ID of attachment or attachments to delete.')
+def do_attachment_complete(cs, args):
+    """Complete an attachment for a cinder volume."""
+    for attachment in args.attachment:
+        cs.attachments.complete(attachment)
+
+
 @api_versions.wraps('3.0')
 def do_version_list(cs, args):
     """List all API versions."""