diff --git a/Lib/test/test_urllib2.py b/Lib/test/test_urllib2.py
index 911a0af9ecf..3ace66e9a6a 100644
--- a/Lib/test/test_urllib2.py
+++ b/Lib/test/test_urllib2.py
@@ -1227,11 +1227,12 @@ def test_basic_auth_with_unquoted_realm(self):
             401, 'WWW-Authenticate: Basic realm=%s\r\n\r\n' % realm)
         opener.add_handler(auth_handler)
         opener.add_handler(http_handler)
-        self._test_basic_auth(opener, auth_handler, "Authorization",
-                              realm, http_handler, password_manager,
-                              "http://acme.example.com/protected",
-                              "http://acme.example.com/protected",
-                              )
+        with self.assertWarns(UserWarning):
+            self._test_basic_auth(opener, auth_handler, "Authorization",
+                                realm, http_handler, password_manager,
+                                "http://acme.example.com/protected",
+                                "http://acme.example.com/protected",
+                                )
 
     def test_proxy_basic_auth(self):
         opener = OpenerDirector()
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index cbcbe1ae373..0035e7067fd 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -95,6 +95,7 @@
 import sys
 import time
 import collections
+import warnings
 
 from urllib.error import URLError, HTTPError, ContentTooShortError
 from urllib.parse import (
@@ -827,6 +828,9 @@ def http_error_auth_reqed(self, authreq, host, req, headers):
             mo = AbstractBasicAuthHandler.rx.search(authreq)
             if mo:
                 scheme, quote, realm = mo.groups()
+                if quote not in ["'", '"']:
+                    warnings.warn("Basic Auth Realm was unquoted",
+                                  UserWarning, 2)
                 if scheme.lower() == 'basic':
                     response = self.retry_http_basic_auth(host, req, realm)
                     if response and response.code != 401: