diff --git a/Lib/html/parser.py b/Lib/html/parser.py
index a65478058f4..9db8ab582be 100644
--- a/Lib/html/parser.py
+++ b/Lib/html/parser.py
@@ -187,17 +187,10 @@ class HTMLParser(_markupbase.ParserBase):
                 elif startswith("<?", i):
                     k = self.parse_pi(i)
                 elif startswith("<!", i):
-                    # this might fail with things like <! not a comment > or
-                    # <! -- space before '--' -->.  When strict is True an
-                    # error is raised, when it's False they will be considered
-                    # as bogus comments and parsed (see parse_bogus_comment).
                     if self.strict:
                         k = self.parse_declaration(i)
                     else:
-                        try:
-                            k = self.parse_declaration(i)
-                        except HTMLParseError:
-                            k = self.parse_bogus_comment(i)
+                        k = self.parse_html_declaration(i)
                 elif (i + 1) < n:
                     self.handle_data("<")
                     k = i + 1
@@ -269,6 +262,27 @@ class HTMLParser(_markupbase.ParserBase):
             i = self.updatepos(i, n)
         self.rawdata = rawdata[i:]
 
+    # Internal -- parse html declarations, return length or -1 if not terminated
+    # See w3.org/TR/html5/tokenization.html#markup-declaration-open-state
+    # See also parse_declaration in _markupbase
+    def parse_html_declaration(self, i):
+        rawdata = self.rawdata
+        if rawdata[i:i+2] != '<!':
+            self.error('unexpected call to parse_html_declaration()')
+        if rawdata[i:i+4] == '<!--':
+            return self.parse_comment(i)
+        elif rawdata[i:i+3] == '<![':
+            return self.parse_marked_section(i)
+        elif rawdata[i:i+9].lower() == '<!doctype':
+            # find the closing >
+            gtpos = rawdata.find('>', 9)
+            if gtpos == -1:
+                return -1
+            self.handle_decl(rawdata[i+2:gtpos])
+            return gtpos+1
+        else:
+            return self.parse_bogus_comment(i)
+
     # Internal -- parse bogus comment, return length or -1 if not terminated
     # see http://www.w3.org/TR/html5/tokenization.html#bogus-comment-state
     def parse_bogus_comment(self, i, report=1):
diff --git a/Lib/test/test_htmlparser.py b/Lib/test/test_htmlparser.py
index 2e7277e573d..1da2ce4f9b7 100644
--- a/Lib/test/test_htmlparser.py
+++ b/Lib/test/test_htmlparser.py
@@ -93,7 +93,7 @@ class TestCaseBase(unittest.TestCase):
 
     def _parse_error(self, source):
         def parse(source=source):
-            parser = html.parser.HTMLParser()
+            parser = self.get_collector()
             parser.feed(source)
             parser.close()
         self.assertRaises(html.parser.HTMLParseError, parse)
@@ -122,7 +122,7 @@ comment1b-->
 <Img sRc='Bar' isMAP>sample
 text
 &#x201C;
-<!--comment2a-- --comment2b--><!>
+<!--comment2a-- --comment2b-->
 </Html>
 """, [
     ("data", "\n"),
@@ -157,24 +157,6 @@ text
             ("data", " foo"),
             ])
 
-    def test_doctype_decl(self):
-        inside = """\
-DOCTYPE html [
-  <!ELEMENT html - O EMPTY>
-  <!ATTLIST html
-      version CDATA #IMPLIED
-      profile CDATA 'DublinCore'>
-  <!NOTATION datatype SYSTEM 'http://xml.python.org/notations/python-module'>
-  <!ENTITY myEntity 'internal parsed entity'>
-  <!ENTITY anEntity SYSTEM 'http://xml.python.org/entities/something.xml'>
-  <!ENTITY % paramEntity 'name|name|name'>
-  %paramEntity;
-  <!-- comment -->
-]"""
-        self._run_check("<!%s>" % inside, [
-            ("decl", inside),
-            ])
-
     def test_bad_nesting(self):
         # Strangely, this *is* supposed to test that overlapping
         # elements are allowed.  HTMLParser is more geared toward
@@ -247,6 +229,30 @@ DOCTYPE html [
         self._parse_error("<a foo='>'")
         self._parse_error("<a foo='>")
 
+    def test_valid_doctypes(self):
+        # from http://www.w3.org/QA/2002/04/valid-dtd-list.html
+        dtds = ['HTML',  # HTML5 doctype
+                ('HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" '
+                 '"http://www.w3.org/TR/html4/strict.dtd"'),
+                ('HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" '
+                 '"http://www.w3.org/TR/html4/loose.dtd"'),
+                ('html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" '
+                 '"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"'),
+                ('html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" '
+                 '"http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd"'),
+                ('math PUBLIC "-//W3C//DTD MathML 2.0//EN" '
+                 '"http://www.w3.org/Math/DTD/mathml2/mathml2.dtd"'),
+                ('html PUBLIC "-//W3C//DTD '
+                 'XHTML 1.1 plus MathML 2.0 plus SVG 1.1//EN" '
+                 '"http://www.w3.org/2002/04/xhtml-math-svg/xhtml-math-svg.dtd"'),
+                ('svg PUBLIC "-//W3C//DTD SVG 1.1//EN" '
+                 '"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"'),
+                'html PUBLIC "-//IETF//DTD HTML 2.0//EN"',
+                'html PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"']
+        for dtd in dtds:
+            self._run_check("<!DOCTYPE %s>" % dtd,
+                            [('decl', 'DOCTYPE ' + dtd)])
+
     def test_declaration_junk_chars(self):
         self._parse_error("<!DOCTYPE foo $ >")
 
@@ -368,6 +374,29 @@ class HTMLParserTolerantTestCase(HTMLParserStrictTestCase):
                             ('comment', '/img'),
                             ('endtag', 'html<')])
 
+    def test_starttag_junk_chars(self):
+        self._run_check("</>", [])
+        self._run_check("</$>", [('comment', '$')])
+        self._run_check("</", [('data', '</')])
+        self._run_check("</a", [('data', '</a')])
+        # XXX this might be wrong
+        self._run_check("<a<a>", [('data', '<a'), ('starttag', 'a', [])])
+        self._run_check("</a<a>", [('endtag', 'a<a')])
+        self._run_check("<!", [('data', '<!')])
+        self._run_check("<a", [('data', '<a')])
+        self._run_check("<a foo='bar'", [('data', "<a foo='bar'")])
+        self._run_check("<a foo='bar", [('data', "<a foo='bar")])
+        self._run_check("<a foo='>'", [('data', "<a foo='>'")])
+        self._run_check("<a foo='>", [('data', "<a foo='>")])
+
+    def test_declaration_junk_chars(self):
+        self._run_check("<!DOCTYPE foo $ >", [('decl', 'DOCTYPE foo $ ')])
+
+    def test_illegal_declarations(self):
+        # XXX this might be wrong
+        self._run_check('<!spacer type="block" height="25">',
+                        [('comment', 'spacer type="block" height="25"')])
+
     def test_with_unquoted_attributes(self):
         # see #12008
         html = ("<html><body bgcolor=d0ca90 text='181008'>"
@@ -476,7 +505,7 @@ class HTMLParserTolerantTestCase(HTMLParserStrictTestCase):
         self._run_check(html, expected)
 
     def test_unescape_function(self):
-        p = html.parser.HTMLParser()
+        p = self.get_collector()
         self.assertEqual(p.unescape('&#bad;'),'&#bad;')
         self.assertEqual(p.unescape('&#0038;'),'&')
         # see #12888
@@ -486,11 +515,14 @@ class HTMLParserTolerantTestCase(HTMLParserStrictTestCase):
         html = ('<! not really a comment >'
                 '<! not a comment either -->'
                 '<! -- close enough -->'
+                '<!><!<-- this was an empty comment>'
                 '<!!! another bogus comment !!!>')
         expected = [
             ('comment', ' not really a comment '),
             ('comment', ' not a comment either --'),
             ('comment', ' -- close enough --'),
+            ('comment', ''),
+            ('comment', '<-- this was an empty comment'),
             ('comment', '!! another bogus comment !!!'),
         ]
         self._run_check(html, expected)