diff --git a/Lib/HTMLParser.py b/Lib/HTMLParser.py
--- a/Lib/HTMLParser.py
+++ b/Lib/HTMLParser.py
@@ -22,17 +22,18 @@
 starttagopen = re.compile('<[a-zA-Z]')
 piclose = re.compile('>')
 commentclose = re.compile(r'--\s*>')
-tagfind = re.compile('([a-zA-Z][-.a-zA-Z0-9:_]*)(?:\s|/(?!>))*')
+
 # see http://www.w3.org/TR/html5/tokenization.html#tag-open-state
 # and http://www.w3.org/TR/html5/tokenization.html#tag-name-state
-tagfind_tolerant = re.compile('[a-zA-Z][^\t\n\r\f />\x00]*')
+# note: if you change tagfind/attrfind remember to update locatestarttagend too
+tagfind = re.compile('([a-zA-Z][^\t\n\r\f />\x00]*)(?:\s|/(?!>))*')
 
 attrfind = re.compile(
     r'((?<=[\'"\s/])[^\s/>][^\s/=>]*)(\s*=+\s*'
     r'(\'[^\']*\'|"[^"]*"|(?![\'"])[^>\s]*))?(?:\s|/(?!>))*')
 
 locatestarttagend = re.compile(r"""
-  <[a-zA-Z][-.a-zA-Z0-9:_]*          # tag name
+  <[a-zA-Z][^\t\n\r\f />\x00]*       # tag name
   (?:[\s/]*                          # optional whitespace before attribute name
     (?:(?<=['"\s/])[^\s/>][^\s/=>]*  # attribute name
       (?:\s*=+\s*                    # value indicator
@@ -373,14 +374,14 @@
                 self.handle_data(rawdata[i:gtpos])
                 return gtpos
             # find the name: w3.org/TR/html5/tokenization.html#tag-name-state
-            namematch = tagfind_tolerant.match(rawdata, i+2)
+            namematch = tagfind.match(rawdata, i+2)
             if not namematch:
                 # w3.org/TR/html5/tokenization.html#end-tag-open-state
                 if rawdata[i:i+3] == '</>':
                     return i+3
                 else:
                     return self.parse_bogus_comment(i)
-            tagname = namematch.group().lower()
+            tagname = namematch.group(1).lower()
             # consume and ignore other stuff between the name and the >
             # Note: this is not 100% correct, since we might have things like
             # </tag attr=">">, but looking for > after tha name should cover
diff --git a/Lib/test/test_htmlparser.py b/Lib/test/test_htmlparser.py
--- a/Lib/test/test_htmlparser.py
+++ b/Lib/test/test_htmlparser.py
@@ -206,8 +206,7 @@
         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>", [('starttag', 'a<a', [])])
         self._run_check("</a<a>", [('endtag', 'a<a')])
         self._run_check("<!", [('data', '<!')])
         self._run_check("<a", [('data', '<a')])
@@ -215,6 +214,11 @@
         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='>")])
+        self._run_check("<a$>", [('starttag', 'a$', [])])
+        self._run_check("<a$b>", [('starttag', 'a$b', [])])
+        self._run_check("<a$b/>", [('startendtag', 'a$b', [])])
+        self._run_check("<a$b  >", [('starttag', 'a$b', [])])
+        self._run_check("<a$b  />", [('startendtag', 'a$b', [])])
 
     def test_valid_doctypes(self):
         # from http://www.w3.org/QA/2002/04/valid-dtd-list.html