diff --git a/zunclient/common/utils.py b/zunclient/common/utils.py
index c9382564..2876e20b 100644
--- a/zunclient/common/utils.py
+++ b/zunclient/common/utils.py
@@ -200,10 +200,12 @@ def parse_command(command):
 
 def parse_mounts(mounts):
     err_msg = ("Invalid mounts argument '%s'. mounts arguments must be of "
-               "the form --mount source=<volume>,destination=<path>.")
+               "the form --mount source=<volume>,destination=<path>. Or use "
+               "--mount size=<size>,destination=<path> to create a new volume "
+               "and mount to the container")
     parsed_mounts = []
     for mount in mounts:
-        mount_info = {"source": "", "destination": ""}
+        mount_info = {"source": "", "destination": "", "size": ""}
         for mnt in mount.split(","):
             try:
                 k, v = mnt.split("=", 1)
@@ -218,7 +220,10 @@ def parse_mounts(mounts):
             else:
                 raise apiexec.CommandError(err_msg % mnt)
 
-        if not mount_info['source'] or not mount_info['destination']:
+        if not mount_info['destination']:
+            raise apiexec.CommandError(err_msg % mnt)
+
+        if not mount_info['source'] and not mount_info['size']:
             raise apiexec.CommandError(err_msg % mnt)
 
         parsed_mounts.append(mount_info)