diff -up ./msrest/serialization.py.orig ./msrest/serialization.py
--- ./msrest/serialization.py.orig	2018-10-15 18:43:34.000000000 +0000
+++ ./msrest/serialization.py	2018-11-02 00:23:20.092139671 +0000
@@ -27,6 +27,7 @@
 from base64 import b64decode, b64encode
 import calendar
 import datetime
+from distutils.version import LooseVersion, StrictVersion
 import decimal
 from enum import Enum
 import json
@@ -37,6 +38,7 @@ try:
     from urllib import quote  # type: ignore
 except ImportError:
     from urllib.parse import quote  # type: ignore
+import pkg_resources
 import xml.etree.ElementTree as ET
 
 import isodate
@@ -57,6 +59,7 @@ except NameError:
     basestring = str  # type: ignore
 
 _LOGGER = logging.getLogger(__name__)
+_ISODATE_VERSION = pkg_resources.get_distribution("isodate").version
 
 try:
     _long_type = long   # type: ignore
@@ -1712,8 +1715,11 @@ class Deserializer(object):
             attr = attr.text
         if re.search(r"[^\W\d_]", attr, re.I + re.U):
             raise DeserializationError("Date must have only digits and -. Received: %s" % attr)
-        # This must NOT use defaultmonth/defaultday. Using None ensure this raises an exception.
-        return isodate.parse_date(attr, defaultmonth=None, defaultday=None)
+        if LooseVersion(_ISODATE_VERSION) >= LooseVersion("0.6.0"):
+            # This must NOT use defaultmonth/defaultday. Using None ensure this raises an exception.
+            return isodate.parse_date(attr, defaultmonth=None, defaultday=None)
+        else:
+            return isodate.parse_date(attr)
 
     @staticmethod
     def deserialize_rfc(attr):