diff --git a/ChangeLog b/ChangeLog
index 4d75407f24..ce2e8ea5bc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Sun Dec 20 23:43:46 2009  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
+
+	* lib/net/http.rb (HTTPGenericRequest#send_request_with_body_stream):
+	  increased encoding chunk size for POST request with body_stream
+	  (1K -> 16K). patched by Brian Candler. #1284.
+
+	* test/net/http/test_post_io.rb: added for the patch. It's good if a
+	  patch comes with a test.
+
 Sat Dec 19 09:31:25 2009  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
 
 	* lib/set.rb (initialize): Add check that argument is enumerable
diff --git a/lib/net/http.rb b/lib/net/http.rb
index 10ec95018a..5a794e6d9f 100644
--- a/lib/net/http.rb
+++ b/lib/net/http.rb
@@ -1467,6 +1467,8 @@ module Net   #:nodoc:
 
     include HTTPHeader
 
+    BUFSIZE = 16*1024
+
     def initialize(m, reqbody, resbody, path, initheader = nil)
       @method = m
       @request_has_body = reqbody
@@ -1552,12 +1554,12 @@ module Net   #:nodoc:
       supply_default_content_type
       write_header sock, ver, path
       if chunked?
-        while s = f.read(1024)
+        while s = f.read(BUFSIZE)
           sock.write(sprintf("%x\r\n", s.length) << s << "\r\n")
         end
         sock.write "0\r\n\r\n"
       else
-        while s = f.read(1024)
+        while s = f.read(BUFSIZE)
           sock.write s
         end
       end
diff --git a/test/net/http/test_post_io.rb b/test/net/http/test_post_io.rb
new file mode 100644
index 0000000000..c4093f9347
--- /dev/null
+++ b/test/net/http/test_post_io.rb
@@ -0,0 +1,32 @@
+require 'test/unit'
+require 'net/http'
+require 'stringio'
+
+class HTTPPostIOTest < Test::Unit::TestCase
+  def test_post_io_chunk_size
+    t = nil
+    TCPServer.open("127.0.0.1", 0) {|serv|
+      _, port, _, _ = serv.addr
+      t = Thread.new {
+        begin
+          req = Net::HTTP::Post.new("/test.cgi")
+          req['Transfer-Encoding'] = 'chunked'
+          req.body_stream = StringIO.new("\0" * (16 * 1024 + 1))
+          http = Net::HTTP.new("127.0.0.1", port)
+          res = http.start { |http| http.request(req) }
+        rescue EOFError, Errno::EPIPE
+        end
+      }
+      sock = serv.accept
+      begin
+        assert_match(/chunked/, sock.gets("\r\n\r\n"))
+        chunk_header = sock.gets.chomp
+        assert_equal(16 * 1024, chunk_header.to_i(16))
+      ensure
+        sock.close
+      end
+    }
+  ensure
+    t.join if t
+  end
+end