diff -r 513f6dfd3173 Doc/library/socket.rst
--- a/Doc/library/socket.rst	Sun May 01 20:24:59 2011 -0500
+++ b/Doc/library/socket.rst	Wed May 04 11:36:09 2011 +0200
@@ -662,8 +662,8 @@
 .. method:: socket.listen(backlog)
 
    Listen for connections made to the socket.  The *backlog* argument specifies the
-   maximum number of queued connections and should be at least 1; the maximum value
-   is system-dependent (usually 5).
+   maximum number of queued connections and should be at least 0; the maximum value
+   is system-dependent (usually 5), the minimum value is forced to 0.
 
 
 .. method:: socket.makefile(mode='r', buffering=None, *, encoding=None, \
diff -r 513f6dfd3173 Lib/test/test_socket.py
--- a/Lib/test/test_socket.py	Sun May 01 20:24:59 2011 -0500
+++ b/Lib/test/test_socket.py	Wed May 04 11:36:09 2011 +0200
@@ -2009,10 +2009,26 @@
             self.checkNonblock(s, False)
         socket.setdefaulttimeout(t)
 
+class SocketListenBacklog0Test(unittest.TestCase):
+    """Socket tests for client-server connection to verify whether
+    a backlog of 0 works for socket.listen().
+    """
+
+    def __init__(self, methodName = 'runTest'):
+        unittest.TestCase.__init__(self, methodName = methodName)
+
+    def testListenBacklog0(self):
+        srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        port = support.bind_port(srv)
+        # backlog = 0
+        srv.listen(0)
+        srv.close()
+
 
 def test_main():
     tests = [GeneralModuleTests, BasicTCPTest, TCPCloserTest, TCPTimeoutTest,
-             TestExceptions, BufferIOTest, BasicTCPTest2, BasicUDPTest, UDPTimeoutTest ]
+             TestExceptions, BufferIOTest, BasicTCPTest2, BasicUDPTest, UDPTimeoutTest,
+             SocketListenBacklog0Test]
 
     tests.extend([
         NonBlockingTCPTests,
diff -r 513f6dfd3173 Modules/socketmodule.c
--- a/Modules/socketmodule.c	Sun May 01 20:24:59 2011 -0500
+++ b/Modules/socketmodule.c	Wed May 04 11:36:09 2011 +0200
@@ -2220,8 +2220,10 @@
     if (backlog == -1 && PyErr_Occurred())
         return NULL;
     Py_BEGIN_ALLOW_THREADS
-    if (backlog < 1)
-        backlog = 1;
+    /* To avoid problems on systems that don't allow a negative backlog
+     * (which doesn't make sense anyway) we force a minimum value of 0. */
+    if (backlog < 0)
+        backlog = 0;
     res = listen(s->sock_fd, backlog);
     Py_END_ALLOW_THREADS
     if (res < 0)
@@ -2234,8 +2236,9 @@
 "listen(backlog)\n\
 \n\
 Enable a server to accept connections.  The backlog argument must be at\n\
-least 1; it specifies the number of unaccepted connection that the system\n\
-will allow before refusing new connections.");
+least 0 (if it is lower, it is set to 0); it specifies the number of\n\
+unaccepted connections that the system will allow before refusing new\n\
+connections.");
 
 
 /*