diff --git a/Lib/http/server.py b/Lib/http/server.py
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -82,16 +82,17 @@ XXX To do:
 
 __version__ = "0.6"
 
 __all__ = [
     "HTTPServer", "BaseHTTPRequestHandler",
     "SimpleHTTPRequestHandler", "CGIHTTPRequestHandler",
 ]
 
+import email.utils
 import html
 import http.client
 import io
 import mimetypes
 import os
 import posixpath
 import select
 import shutil
@@ -561,22 +562,17 @@ class BaseHTTPRequestHandler(socketserve
     def version_string(self):
         """Return the server software version string."""
         return self.server_version + ' ' + self.sys_version
 
     def date_time_string(self, timestamp=None):
         """Return the current date and time formatted for a message header."""
         if timestamp is None:
             timestamp = time.time()
-        year, month, day, hh, mm, ss, wd, y, z = time.gmtime(timestamp)
-        s = "%s, %02d %3s %4d %02d:%02d:%02d GMT" % (
-                self.weekdayname[wd],
-                day, self.monthname[month], year,
-                hh, mm, ss)
-        return s
+        return email.utils.formatdate(timestamp, usegmt=True)
 
     def log_date_time_string(self):
         """Return the current time formatted for logging."""
         now = time.time()
         year, month, day, hh, mm, ss, x, y, z = time.localtime(now)
         s = "%02d/%3s/%04d %02d:%02d:%02d" % (
                 day, self.monthname[month], year, hh, mm, ss)
         return s
diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
--- a/Lib/test/test_httpservers.py
+++ b/Lib/test/test_httpservers.py
@@ -12,16 +12,17 @@ import os
 import sys
 import re
 import base64
 import shutil
 import urllib.parse
 import html
 import http.client
 import tempfile
+import time
 from io import BytesIO
 
 import unittest
 from test import support
 threading = support.import_module('threading')
 
 class NoLogRequestHandler:
     def log_message(self, *args):
@@ -868,16 +869,29 @@ class BaseHTTPRequestHandlerTestCase(uni
         close_values = iter((True,))
         self.handler.handle()
         self.assertRaises(StopIteration, next, close_values)
 
         close_values = iter((False, False, True))
         self.handler.handle()
         self.assertRaises(StopIteration, next, close_values)
 
+    def test_date_time_string(self):
+        now = time.time()
+        # this is the old code that formats the timestamp
+        year, month, day, hh, mm, ss, wd, y, z = time.gmtime(now)
+        expected = "%s, %02d %3s %4d %02d:%02d:%02d GMT" % (
+            self.handler.weekdayname[wd],
+            day,
+            self.handler.monthname[month],
+            year, hh, mm, ss
+        )
+        self.assertEqual(self.handler.date_time_string(timestamp=now), expected)
+
+
 class SimpleHTTPRequestHandlerTestCase(unittest.TestCase):
     """ Test url parsing """
     def setUp(self):
         self.translated = os.getcwd()
         self.translated = os.path.join(self.translated, 'filename')
         self.handler = SocketlessRequestHandler()
 
     def test_query_arguments(self):