diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index c68fe54b939..cea153e907a 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -557,6 +557,7 @@ def test_unquoting(self):
                          "%s" % result)
         self.assertRaises((TypeError, AttributeError), urllib.parse.unquote, None)
         self.assertRaises((TypeError, AttributeError), urllib.parse.unquote, ())
+        self.assertRaises((TypeError, AttributeError), urllib.parse.unquote, b'')
 
     def test_unquoting_badpercent(self):
         # Test unquoting on bad percent-escapes
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index a9fa26ad8f6..133b9d99b60 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -338,7 +338,7 @@ def unquote(string, encoding='utf-8', errors='replace'):
 
     unquote('abc%20def') -> 'abc def'.
     """
-    if string in (b'', ''):
+    if string == '':
         return string
     res = string.split('%')
     if len(res) == 1: