diff -r ad6be34ce8c9 Lib/test/test_urlparse.py
--- a/Lib/test/test_urlparse.py	Tue Apr 26 01:56:50 2016 +0200
+++ b/Lib/test/test_urlparse.py	Mon Apr 25 23:39:03 2016 -0400
@@ -627,6 +627,23 @@
                         with self.assertRaises(ValueError):
                             p.port
 
+    def test_invalid_args(self):
+        default_url = 'www.python.org'
+        invalid_args = [
+            (999, 'http'),
+            ({}, 'http'),
+            ([], 'http'),
+            ((), 'http'),
+            (default_url, 999),
+            (default_url, {}),
+            (default_url, []),
+            (default_url, ())
+            ]
+
+        for arg1, arg2 in invalid_args:
+            with self.assertRaises(TypeError):
+                urllib.parse.urlparse(arg1, arg2)
+
     def test_attributes_without_netloc(self):
         # This example is straight from RFC 3261.  It looks like it
         # should allow the username, hostname, and port to be filled
diff -r ad6be34ce8c9 Lib/urllib/parse.py
--- a/Lib/urllib/parse.py	Tue Apr 26 01:56:50 2016 +0200
+++ b/Lib/urllib/parse.py	Mon Apr 25 23:39:03 2016 -0400
@@ -95,7 +95,16 @@
 
 def _decode_args(args, encoding=_implicit_encoding,
                        errors=_implicit_errors):
-    return tuple(x.decode(encoding, errors) if x else '' for x in args)
+    return tuple(x.decode(encoding, errors) if x != '' else '' for x in args)
+
+def _str_like(x):
+    if hasattr(x, 'encode'):
+        return True
+    elif hasattr(x, 'decode'):
+        return False
+    else:
+        raise TypeError('Arguments must be all str or all bytes like objects, '
+                        '{!r} is invalid'.format(x))
 
 def _coerce_args(*args):
     # Invokes decode if necessary to create str args
@@ -103,12 +112,12 @@
     # an appropriate result coercion function
     #   - noop for str inputs
     #   - encoding function otherwise
-    str_input = isinstance(args[0], str)
-    for arg in args[1:]:
-        # We special-case the empty string to support the
-        # "scheme=''" default argument to some functions
-        if arg and isinstance(arg, str) != str_input:
-            raise TypeError("Cannot mix str and non-str arguments")
+    str_input = _str_like(args[0])
+
+    # We special-case the empty string to support the
+    # "scheme=''" default argument to some functions
+    if any(_str_like(x) != str_input for x in args[1:] if x != ''):
+        raise TypeError('Cannot mix str and non-str arguments')
     if str_input:
         return args + (_noop,)
     return _decode_args(args) + (_encode_result,)