diff -r 0ad7eb75152a Lib/test/test_signal.py
--- a/Lib/test/test_signal.py	Sun Jul 27 15:51:36 2014 +0200
+++ b/Lib/test/test_signal.py	Sun Jul 27 16:08:38 2014 +0200
@@ -262,12 +262,31 @@ class WakeupFDTests(unittest.TestCase):
         r2, w2 = os.pipe()
         self.addCleanup(os.close, r2)
         self.addCleanup(os.close, w2)
+        os.set_blocking(w1, False)
+        os.set_blocking(w2, False)
 
         signal.set_wakeup_fd(w1)
         self.assertEqual(signal.set_wakeup_fd(w2), w1)
         self.assertEqual(signal.set_wakeup_fd(-1), w2)
         self.assertEqual(signal.set_wakeup_fd(-1), -1)
 
+    def test_set_wakeup_fd_blocking(self):
+        rfd, wfd = os.pipe()
+        self.addCleanup(os.close, rfd)
+        self.addCleanup(os.close, wfd)
+
+        # fd must be non-blocking
+        os.set_blocking(wfd, True)
+        with self.assertRaises(ValueError) as cm:
+            signal.set_wakeup_fd(wfd)
+        self.assertEqual(str(cm.exception),
+                         "the fd must be in non-blocking mode")
+
+        # non-blocking is ok
+        os.set_blocking(wfd, False)
+        signal.set_wakeup_fd(wfd)
+        signal.set_wakeup_fd(-1)
+
 
 @unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
 class WakeupSignalTests(unittest.TestCase):
@@ -328,7 +347,7 @@ class WakeupSignalTests(unittest.TestCas
 
         signal.signal(signal.SIGALRM, handler)
         r, w = os.pipe()
-        os.set_blocking(w, False)
+        os.set_blocking(r, False)
 
         # Set wakeup_fd a read-only file descriptor to trigger the error
         signal.set_wakeup_fd(r)
diff -r 0ad7eb75152a Modules/signalmodule.c
--- a/Modules/signalmodule.c	Sun Jul 27 15:51:36 2014 +0200
+++ b/Modules/signalmodule.c	Sun Jul 27 16:08:38 2014 +0200
@@ -439,6 +439,8 @@ signal_set_wakeup_fd(PyObject *self, PyO
 #endif
 
     if (fd != -1) {
+        int blocking;
+
         if (!_PyVerify_fd(fd)) {
             PyErr_SetString(PyExc_ValueError, "invalid fd");
             return NULL;
@@ -446,6 +448,17 @@ signal_set_wakeup_fd(PyObject *self, PyO
 
         if (fstat(fd, &buf) != 0)
             return PyErr_SetFromErrno(PyExc_OSError);
+
+#ifndef MS_WINDOWS
+        blocking = _Py_get_blocking(fd);
+        if (blocking < 0)
+            return NULL;
+#endif
+        if (blocking) {
+            PyErr_SetString(PyExc_ValueError,
+                            "the fd must be in non-blocking mode");
+            return NULL;
+        }
     }
 
     old_fd = wakeup_fd;