diff -r 1947cca7f583 Doc/library/http.client.rst
--- a/Doc/library/http.client.rst	Tue Mar 08 22:54:11 2011 +0000
+++ b/Doc/library/http.client.rst	Wed Mar 09 13:06:08 2011 +1100
@@ -433,7 +433,11 @@
 .. method:: HTTPConnection.set_tunnel(host, port=None, headers=None)
 
    Set the host and the port for HTTP Connect Tunnelling. Normally used when it
-   is required to a HTTPS Connection through a proxy server.
+   is required to access a HTTPS Connection through a proxy server.
+
+   The host and port arguments specify the endpoint of the tunnelled connection
+   (i.e. the address included in the CONNECT request, *not* the address of
+   the proxy server).
 
    The headers argument should be a mapping of extra HTTP headers to to sent
    with the CONNECT request.