diff --git a/Lib/test/test_xmlrpc.py b/Lib/test/test_xmlrpc.py
index 7c68e4c..d1ed40f 100644
--- a/Lib/test/test_xmlrpc.py
+++ b/Lib/test/test_xmlrpc.py
@@ -135,6 +135,14 @@
                           xmlrpclib.loads(strg)[0][0])
         self.assertRaises(TypeError, xmlrpclib.dumps, (arg1,))
 
+    def test_get_host_info(self):
+        # see bug #3613, this raised a TypeError
+        transp = xmlrpc.client.Transport()
+        self.assertEquals(transp.get_host_info("user@host.tld"),
+                          ('host.tld',
+                           [('Authorization', 'Basic dXNlcg==')], {}))
+
+
 class HelperTestCase(unittest.TestCase):
     def test_escape(self):
         self.assertEqual(xmlrpclib.escape("a&b"), "a&amp;b")
diff --git a/Lib/xmlrpc/client.py b/Lib/xmlrpc/client.py
index e66ee84..86988de 100644
--- a/Lib/xmlrpc/client.py
+++ b/Lib/xmlrpc/client.py
@@ -1161,7 +1161,8 @@
 
         if auth:
             import base64
-            auth = base64.encodestring(urllib.parse.unquote(auth))
+            auth = urllib.parse.unquote_to_bytes(auth)
+            auth = base64.encodestring(auth).decode("utf-8")
             auth = "".join(auth.split()) # get rid of whitespace
             extra_headers = [
                 ("Authorization", "Basic " + auth)