diff --git a/owslib/iso.py b/owslib/iso.py
index c2b5b26bd..c69b1bc1e 100644
--- a/owslib/iso.py
+++ b/owslib/iso.py
@@ -717,12 +717,29 @@ def __init__(self, md=None):
 
 class MD_ReferenceSystem(object):
     """ process MD_ReferenceSystem """
-    def __init__(self, md):
+    def __init__(self, md=None):
         if md is None:
-            pass
+            self.code = None
+            self.codeSpace = None
+            self.version = None
         else:
             val = md.find(util.nspath_eval('gmd:referenceSystemIdentifier/gmd:RS_Identifier/gmd:code/gco:CharacterString', namespaces))
-            self.code = util.testXMLValue(val)
+            if val is not None:
+                self.code = util.testXMLValue(val)
+            else:
+                self.code = None
+
+            val = md.find(util.nspath_eval('gmd:referenceSystemIdentifier/gmd:RS_Identifier/gmd:codeSpace/gco:CharacterString', namespaces))
+            if val is not None:
+                self.codeSpace = util.testXMLValue(val)
+            else:
+                self.codeSpace = None
+
+            val = md.find(util.nspath_eval('gmd:referenceSystemIdentifier/gmd:RS_Identifier/gmd:version/gco:CharacterString', namespaces))
+            if val is not None:
+                self.version = util.testXMLValue(val)
+            else:
+                self.version = None
 
 def _testCodeListValue(elpath):
     """ get gco:CodeListValue_Type attribute, else get text content """
diff --git a/tests/doctests/iso_creation.txt b/tests/doctests/iso_creation.txt
index d36cd412d..1cbe19400 100644
--- a/tests/doctests/iso_creation.txt
+++ b/tests/doctests/iso_creation.txt
@@ -3,7 +3,7 @@ Imports
     >>> from __future__ import (absolute_import, division, print_function)
     >>> import urllib2
     >>> from owslib.etree import etree
-    >>> from owslib.iso import MD_Metadata, MD_DataIdentification, CI_ResponsibleParty
+    >>> from owslib.iso import MD_Metadata, MD_DataIdentification, CI_ResponsibleParty, MD_ReferenceSystem
 
 Print testing of various ISO fields
 
@@ -21,6 +21,10 @@ Print testing of various ISO fields
 	>>> md.identifier = '286c0725-146e-4533-b1bf-d6e367f6c342'
 	>>> md.identification.topiccategory.append('biota')
 	>>> md.identification.topiccategory.append('environment')
+	>>> md.referencesystem = MD_ReferenceSystem()
+	>>> md.referencesystem.code = '4326'
+	>>> md.referencesystem.codeSpace = 'urn:ogc:def:crs:EPSG'
+	>>> md.referencesystem.version = '6.11.2'
 	>>> kw = {}
 	>>> kw['keywords'] = []
 	>>> kw['keywords'].append('Agricultural and aquaculture facilities')