Index: test/socket/test_socket.rb
===================================================================
--- test/socket/test_socket.rb	(revision 26621)
+++ test/socket/test_socket.rb	(working copy)
@@ -4,6 +4,8 @@
 rescue LoadError
 end
 
+require 'timeout'
+
 class TestBasicSocket < Test::Unit::TestCase
   def inet_stream
     sock = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
@@ -71,6 +73,47 @@
       }
     end
   end
+
+  def test_use_all_available
+
+    no_files = 0
+
+    server_ports = []
+    clients = []
+
+    deplete_fds = []
+    begin
+      Timeout::timeout(20) do
+        begin
+          while true
+            another_server = TCPServer.new 'localhost', nil
+            port = another_server.addr[1]
+            client = TCPSocket.new('localhost', port)
+            server_ports << another_server.accept
+            clients << client
+            client.write clients.length
+          end
+        rescue Exception => e
+          # expected
+        end
+
+        number_returned = 0
+        while number_returned < clients.length
+          r,w,e = select(server_ports, nil, nil, nil)
+          for readable in r
+            read = readable.recv 1024
+            readable.write read
+            number_returned += 1
+          end
+        end
+
+        clients.each_with_index{|client, idx|
+          received = client.recv(1024)
+          assert_equal(received, (idx + 1).to_s)
+        }
+      end
+    end
+  end
 end if defined?(Socket)
 
 class TestSocket < Test::Unit::TestCase
Index: win32/win32.h
===================================================================
--- win32/win32.h	(revision 26621)
+++ win32/win32.h	(working copy)
@@ -23,6 +23,9 @@
 #ifdef __BORLANDC__
 #define USE_WINSOCK2
 #endif
+#ifndef FD_SETSIZE
+# define FD_SETSIZE 256 // larger default
+#endif
 #ifdef USE_WINSOCK2
 #include <winsock2.h>
 #include <ws2tcpip.h>