diff --git a/src/odf/odfmanifest.py b/src/odf/odfmanifest.py
index f0afeadc67..fe1b9bb411 100644
--- a/src/odf/odfmanifest.py
+++ b/src/odf/odfmanifest.py
@@ -25,7 +25,7 @@ import zipfile
 from xml.sax import make_parser,handler
 from xml.sax.xmlreader import InputSource
 import xml.sax.saxutils
-from cStringIO import StringIO
+import io
 
 MANIFESTNS="urn:oasis:names:tc:opendocument:xmlns:manifest:1.0"
 
@@ -97,7 +97,7 @@ def manifestlist(manifestxml):
     parser.setErrorHandler(handler.ErrorHandler())
 
     inpsrc = InputSource()
-    inpsrc.setByteStream(StringIO(manifestxml))
+    inpsrc.setByteStream(io.BytesIO(manifestxml))
     parser.setFeature(handler.feature_external_ges, False)  # Changed by Kovid to ignore external DTDs
     parser.parse(inpsrc)
 
@@ -114,4 +114,3 @@ if __name__ == "__main__":
     result = odfmanifest(sys.argv[1])
     for file in result.values():
         print("%-40s %-40s" % (file['media-type'], file['full-path']))
-
diff --git a/src/odf/opendocument.py b/src/odf/opendocument.py
index 0de129bf21..023f330e88 100644
--- a/src/odf/opendocument.py
+++ b/src/odf/opendocument.py
@@ -29,6 +29,7 @@ import element
 from attrconverters import make_NCName
 from xml.sax.xmlreader import InputSource
 from odfmanifest import manifestlist
+from polyglot.io import PolyglotBytesIO
 
 __version__= TOOLSVERSION
 
@@ -151,13 +152,13 @@ class OpenDocument:
             self._styles_dict[name] = element
 
     def toXml(self, filename=''):
-        xml=StringIO()
+        xml=PolyglotBytesIO()
         xml.write(_XMLPROLOGUE)
         self.body.toXml(0, xml)
         if not filename:
             return xml.getvalue()
         else:
-            f=file(filename,'w')
+            f=file(filename,'wb')
             f.write(xml.getvalue())
             f.close()
 
@@ -166,7 +167,7 @@ class OpenDocument:
             Always written as a bytestream in UTF-8 encoding
         """
         self.__replaceGenerator()
-        xml=StringIO()
+        xml=PolyglotBytesIO()
         xml.write(_XMLPROLOGUE)
         self.topnode.toXml(0, xml)
         return xml.getvalue()