diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
index 90c8d6922629e8..d2ec0dadbcb071 100644
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -891,6 +891,8 @@ def test_parse_qs_separator(self):
             with self.subTest(f"Original: {orig!r}, Expected: {expect!r}"):
                 result = urllib.parse.parse_qs(orig, separator=';')
                 self.assertEqual(result, expect, "Error parsing %r" % orig)
+                result_bytes = urllib.parse.parse_qs(orig, separator=b';')
+                self.assertEqual(result_bytes, expect, "Error parsing %r" % orig)
 
 
     def test_parse_qsl_separator(self):
@@ -910,6 +912,8 @@ def test_parse_qsl_separator(self):
             with self.subTest(f"Original: {orig!r}, Expected: {expect!r}"):
                 result = urllib.parse.parse_qsl(orig, separator=';')
                 self.assertEqual(result, expect, "Error parsing %r" % orig)
+                result_bytes = urllib.parse.parse_qsl(orig, separator=b';')
+                self.assertEqual(result_bytes, expect, "Error parsing %r" % orig)
 
 
     def test_urlencode_sequences(self):
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 0c1c94f5fc986b..36fd8fe2803e22 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -721,6 +721,7 @@ def parse_qsl(qs, keep_blank_values=False, strict_parsing=False,
         Returns a list, as G-d intended.
     """
     qs, _coerce_result = _coerce_args(qs)
+    separator, _ = _coerce_args(separator)
 
     if not separator or (not isinstance(separator, (str, bytes))):
         raise ValueError("Separator must be of type string or bytes.")
diff --git a/Misc/NEWS.d/next/Library/2021-03-11-00-31-41.bpo-42967.2PeQRw.rst b/Misc/NEWS.d/next/Library/2021-03-11-00-31-41.bpo-42967.2PeQRw.rst
new file mode 100644
index 00000000000000..f8ad3eaaedd785
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-03-11-00-31-41.bpo-42967.2PeQRw.rst
@@ -0,0 +1,3 @@
+Allow :class:`bytes` ``separator`` argument in ``urllib.parse.parse_qs`` and
+``urllib.parse.parse_qsl`` when parsing :class:`str` query strings.  Previously,
+this raised a ``TypeError``.