diff --git a/Lib/BaseHTTPServer.py b/Lib/BaseHTTPServer.py
index deaf2f960b8..ce9ade963e9 100644
--- a/Lib/BaseHTTPServer.py
+++ b/Lib/BaseHTTPServer.py
@@ -365,7 +365,7 @@ class BaseHTTPRequestHandler(SocketServer.StreamRequestHandler):
         # using _quote_html to prevent Cross Site Scripting attacks (see bug #1100201)
         content = (self.error_message_format %
                    {'code': code, 'message': _quote_html(message), 'explain': explain})
-        self.send_response(code, message)
+        self.send_response(code, short)
         self.send_header("Content-Type", self.error_content_type)
         self.send_header('Connection', 'close')
         self.end_headers()
diff --git a/Misc/NEWS b/Misc/NEWS
index 588a5c64025..8b90f7c841e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -214,6 +214,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #12921: BaseHTTPServer's send_error should send the correct error
+  response message when  send_error includes a message in addition to error
+  status. Patch submitted by Karl.
+
 - Issue #17278: Fix a crash in heapq.heappush() and heapq.heappop() when
   the list is being resized concurrently.