diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
index d90131be8dcccfe..bfbff544e4d46f3 100644
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -1345,6 +1345,11 @@ def test_invalid_bracketed_hosts(self):
                     urllib.parse.urlsplit(case).hostname
                 with self.assertRaises(ValueError):
                     urllib.parse.urlparse(case).hostname
+                bytes_case = case.encode('utf8')
+                with self.assertRaises(ValueError):
+                    urllib.parse.urlsplit(bytes_case).hostname
+                with self.assertRaises(ValueError):
+                    urllib.parse.urlparse(bytes_case).hostname
 
     def test_splitting_bracketed_hosts(self):
         p1 = urllib.parse.urlsplit('scheme://user@[v6a.ip]/path?query')
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 003feab396a2e42..ece30fa338aa33c 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -241,10 +241,15 @@ def _userinfo(self):
     def _hostinfo(self):
         netloc = self.netloc
         _, _, hostinfo = netloc.rpartition(b'@')
-        _, have_open_br, bracketed = hostinfo.partition(b'[')
+        bracket_prefix, have_open_br, bracketed = hostinfo.partition(b'[')
         if have_open_br:
+            if bracket_prefix:
+                raise ValueError('Invalid IPv6 URL')
             hostname, _, port = bracketed.partition(b']')
-            _, _, port = port.partition(b':')
+            _check_bracketed_host(hostname.decode(_implicit_encoding, _implicit_errors))
+            bracket_suffix, _, port = port.partition(b':')
+            if bracket_suffix:
+                raise ValueError('Invalid IPv6 URL')
         else:
             hostname, _, port = hostinfo.partition(b':')
         if not port: