diff -r 89665cc05592 Doc/library/signal.rst
--- a/Doc/library/signal.rst	Tue Jul 22 21:29:52 2014 +0100
+++ b/Doc/library/signal.rst	Wed Jul 23 02:45:06 2014 +0200
@@ -303,13 +303,15 @@ The :mod:`signal` module defines the fol
 
 .. function:: set_wakeup_fd(fd)
 
-   Set the wakeup file descriptor to *fd*.  When a signal is received, the
-   signal number is written as a single byte into the fd.  This can be used by
-   a library to wakeup a poll or select call, allowing the signal to be fully
-   processed.
+   Set the file descriptor *fd* to non-blocking mode and set the wakeup file
+   descriptor to *fd*.
 
-   The old wakeup fd is returned.  *fd* must be non-blocking.  It is up to the
-   library to remove any bytes before calling poll or select again.
+   When a signal is received, the signal number is written as a single byte
+   into the *fd*.  This can be used by a library to wakeup a poll or select
+   call, allowing the signal to be fully processed.
+
+   It is up to the library to remove any bytes before calling poll or select
+   again.
 
    Use for example ``struct.unpack('%uB' % len(data), data)`` to decode the
    signal numbers list.
diff -r 89665cc05592 Include/fileutils.h
--- a/Include/fileutils.h	Tue Jul 22 21:29:52 2014 +0100
+++ b/Include/fileutils.h	Wed Jul 23 02:45:06 2014 +0200
@@ -70,6 +70,8 @@ PyAPI_FUNC(int) _Py_set_inheritable(int 
                                     int *atomic_flag_works);
 
 PyAPI_FUNC(int) _Py_dup(int fd);
+
+PyAPI_FUNC(int) _Py_set_blocking(int fd, int blocking);
 #endif
 
 #ifdef __cplusplus
diff -r 89665cc05592 Lib/test/test_signal.py
--- a/Lib/test/test_signal.py	Tue Jul 22 21:29:52 2014 +0100
+++ b/Lib/test/test_signal.py	Wed Jul 23 02:45:06 2014 +0200
@@ -276,7 +276,6 @@ class WakeupSignalTests(unittest.TestCas
         # use a subprocess to have only one thread
         code = """if 1:
         import _testcapi
-        import fcntl
         import os
         import signal
         import struct
@@ -299,10 +298,6 @@ class WakeupSignalTests(unittest.TestCas
 
         signal.signal(signal.SIGALRM, handler)
         read, write = os.pipe()
-        for fd in (read, write):
-            flags = fcntl.fcntl(fd, fcntl.F_GETFL, 0)
-            flags = flags | os.O_NONBLOCK
-            fcntl.fcntl(fd, fcntl.F_SETFL, flags)
         signal.set_wakeup_fd(write)
 
         test()
@@ -322,7 +317,6 @@ class WakeupSignalTests(unittest.TestCas
         code = """if 1:
         import _testcapi
         import errno
-        import fcntl
         import os
         import signal
         import sys
@@ -333,8 +327,6 @@ class WakeupSignalTests(unittest.TestCas
 
         signal.signal(signal.SIGALRM, handler)
         r, w = os.pipe()
-        flags = fcntl.fcntl(r, fcntl.F_GETFL, 0)
-        fcntl.fcntl(r, fcntl.F_SETFL, flags | os.O_NONBLOCK)
 
         # Set wakeup_fd a read-only file descriptor to trigger the error
         signal.set_wakeup_fd(r)
diff -r 89665cc05592 Modules/signalmodule.c
--- a/Modules/signalmodule.c	Tue Jul 22 21:29:52 2014 +0100
+++ b/Modules/signalmodule.c	Wed Jul 23 02:45:06 2014 +0200
@@ -428,6 +428,10 @@ signal_set_wakeup_fd(PyObject *self, PyO
 {
     struct stat buf;
     int fd, old_fd;
+#ifdef MS_WINDOWS
+    u_long block;
+#endif
+
     if (!PyArg_ParseTuple(args, "i:set_wakeup_fd", &fd))
         return NULL;
 #ifdef WITH_THREAD
@@ -446,6 +450,15 @@ signal_set_wakeup_fd(PyObject *self, PyO
 
         if (fstat(fd, &buf) != 0)
             return PyErr_SetFromErrno(PyExc_OSError);
+
+#ifdef MS_WINDOWS
+        block = 1;
+        if (!ioctlsocket(s->sock_fd, FIONBIO, &block))
+            return PyErr_SetFromWindowsErr(0);
+#else
+        if (_Py_set_blocking(fd, 0) < 0)
+            return NULL;
+#endif
     }
 
     old_fd = wakeup_fd;
diff -r 89665cc05592 Modules/socketmodule.c
--- a/Modules/socketmodule.c	Tue Jul 22 21:29:52 2014 +0100
+++ b/Modules/socketmodule.c	Wed Jul 23 02:45:06 2014 +0200
@@ -548,6 +548,9 @@ set_gaierror(int error)
 static int
 internal_setblocking(PySocketSockObject *s, int block)
 {
+#ifdef MS_WINDOWS
+    u_long arg;
+#endif
 #if !defined(MS_WINDOWS) \
     && !((defined(HAVE_SYS_IOCTL_H) && defined(FIONBIO)))
     int delay_flag, new_delay_flag;
@@ -574,8 +577,8 @@ internal_setblocking(PySocketSockObject 
         fcntl(s->sock_fd, F_SETFL, new_delay_flag);
 #endif
 #else /* MS_WINDOWS */
-    block = !block;
-    ioctlsocket(s->sock_fd, FIONBIO, (u_long*)&block);
+    arg = !block;
+    ioctlsocket(s->sock_fd, FIONBIO, &arg);
 #endif /* MS_WINDOWS */
     Py_END_ALLOW_THREADS
 
diff -r 89665cc05592 Python/fileutils.c
--- a/Python/fileutils.c	Tue Jul 22 21:29:52 2014 +0100
+++ b/Python/fileutils.c	Wed Jul 23 02:45:06 2014 +0200
@@ -1045,3 +1045,36 @@ int
     return fd;
 }
 
+#ifndef MS_WINDOWS
+int
+_Py_set_blocking(int fd, int blocking)
+{
+#if defined(HAVE_SYS_IOCTL_H) && defined(FIONBIO)
+    int arg = !blocking;
+    if (ioctl(fd, FIONBIO, &arg) < 0)
+        goto error;
+#else
+    int flags, res;
+
+    flags = fcntl(fd, F_GETFL, 0);
+    if (flags < 0)
+        goto error;
+
+    if (blocking)
+        flags = flags & (~O_NONBLOCK);
+    else
+        flags = flags | O_NONBLOCK;
+
+    res = fcntl(fd, F_SETFL, flags);
+    if (res < 0)
+        goto error;
+
+#endif
+    return 0;
+
+error:
+    PyErr_SetFromErrno(PyExc_OSError);
+    return -1;
+}
+#endif
+