diff --git a/Lib/test/test_sax.py b/Lib/test/test_sax.py
index 3044960a0ed165..741ff928311364 100644
--- a/Lib/test/test_sax.py
+++ b/Lib/test/test_sax.py
@@ -13,7 +13,8 @@
 from xml.sax.saxutils import XMLGenerator, escape, unescape, quoteattr, \
                              XMLFilterBase, prepare_input_source
 from xml.sax.expatreader import create_parser
-from xml.sax.handler import feature_namespaces, feature_external_ges
+from xml.sax.handler import feature_namespaces, feature_external_ges,\
+    property_xml_string
 from xml.sax.xmlreader import InputSource, AttributesImpl, AttributesNSImpl
 from io import BytesIO, StringIO
 import codecs
@@ -1311,6 +1312,73 @@ def test_nsattrs_wattr(self):
         self.assertEqual(attrs.getQNameByName((ns_uri, "attr")), "ns:attr")
 
 
+# ===========================================================================
+#
+#   Sax parser property tests
+#
+#   Currently only tests the condition reported in issue bpo-6686
+#
+# ===========================================================================
+
+class PropertyContentHandler(ContentHandler):
+    def __init__(self, test_harness, reader, test, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.test_harness = test_harness
+        self.reader = reader
+        self.test_data = test
+
+    def startElement(self, name, attr):
+        property_ = self.reader.getProperty(property_xml_string)
+        self.test_harness.assertIsInstance(property_, bytes)
+        if self.test_harness.test_data is not None:
+            prop = property_
+            self.test_harness\
+                .assertEqual(prop.decode(encoding=self.test_data[0]),
+                             self.test_data[1][1])
+        super().startElement(name, attr)
+
+
+class SaxPropertyTest(unittest.TestCase):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.result = None
+        self.test_data = [['ascii', ['Hello']],
+                          ['utf-8', ['abc˦']],
+                          ['iso-8859-1', ['ghiéñ']]]
+        for t in self.test_data:
+            d = '<test>{}</test>\n'.format(t[1][0])
+            t[1].append(d)
+
+    def test_property_xml_string_from_bytes(self):
+        for prolog in (True, False):
+            for t in self.test_data:
+                reader = create_parser()
+                reader.setContentHandler(PropertyContentHandler(self,
+                                                                reader,
+                                                                t))
+                source = InputSource()
+                data = b''
+                if prolog:
+                    data += b'<?xml version="1.0" encoding="'
+                    data += '{}'.format(t[0]).encode(encoding='ascii')
+                    data += b'"?>\n'
+                data += t[1][1].encode(t[0])
+                source.setByteStream(BytesIO(data))
+                if not prolog:
+                    source.setEncoding(t[0])
+                reader.parse(source)
+                pass
+
+    def test_property_xml_str_from_str(self):
+        self.test_data = None
+        reader = create_parser()
+        reader.setContentHandler(PropertyContentHandler(self,
+                                                        reader,
+                                                        None))
+        in_  = '<?xml version="1.0" encoding="UTF-8"?>\n<test>Hi there</test>'
+        reader.parse(StringIO(in_))
+
+
 def test_main():
     run_unittest(MakeParserTest,
                  ParseTest,
@@ -1323,7 +1391,9 @@ def test_main():
                  StreamReaderWriterXmlgenTest,
                  ExpatReaderTest,
                  ErrorReportingTest,
-                 XmlReaderTest)
+                 XmlReaderTest,
+                 SaxPropertyTest)
+
 
 if __name__ == "__main__":
     test_main()
diff --git a/Lib/xml/sax/expatreader.py b/Lib/xml/sax/expatreader.py
index 5066ffc2fa51f0..48abf5d1d9528e 100644
--- a/Lib/xml/sax/expatreader.py
+++ b/Lib/xml/sax/expatreader.py
@@ -3,8 +3,6 @@
 pyexpat.__version__ == '2.22'.
 """
 
-version = "0.20"
-
 from xml.sax._exceptions import *
 from xml.sax.handler import feature_validation, feature_namespaces
 from xml.sax.handler import feature_namespace_prefixes
@@ -27,6 +25,8 @@
         raise SAXReaderNotAvailable("expat not supported", None)
 from xml.sax import xmlreader, saxutils, handler
 
+version = "0.20"
+
 AttributesImpl = xmlreader.AttributesImpl
 AttributesNSImpl = xmlreader.AttributesNSImpl
 
@@ -266,12 +266,14 @@ def _reset_lex_handler_prop(self):
             parser.EndCdataSectionHandler = None
             parser.StartDoctypeDeclHandler = None
             parser.EndDoctypeDeclHandler = None
+            parser.XmlDeclHandler = None
         else:
             parser.CommentHandler = lex.comment
             parser.StartCdataSectionHandler = lex.startCDATA
             parser.EndCdataSectionHandler = lex.endCDATA
             parser.StartDoctypeDeclHandler = self.start_doctype_decl
             parser.EndDoctypeDeclHandler = lex.endDTD
+            parser.XmlDeclHandler = lex.xml_decl_handler
 
     def reset(self):
         if self._namespaces:
diff --git a/Misc/ACKS b/Misc/ACKS
index 5014584b7bc0b7..28673b82bd210a 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -572,6 +572,7 @@ Chris Gonnerman
 Shelley Gooch
 David Goodger
 Elliot Gorokhovsky
+Jonathan Gossage
 Hans de Graaff
 Tim Graham
 Kim Gräsman