diff -r e78743e03c8f Lib/test/test_devpoll.py
--- a/Lib/test/test_devpoll.py	Fri Dec 13 12:08:55 2013 +0200
+++ b/Lib/test/test_devpoll.py	Fri Dec 13 12:54:09 2013 +0200
@@ -120,6 +120,16 @@
         self.addCleanup(devpoll.close)
         self.assertEqual(os.get_inheritable(devpoll.fileno()), False)
 
+    def test_events_mask_overflow(self):
+        pollster = select.devpoll()
+        w, r = os.pipe()
+        pollster.register(w)
+        # Issue #17919
+        self.assertRaises(OverflowError, pollster.register, 0, -1)
+        self.assertRaises(OverflowError, pollster.register, 0, USHRT_MAX + 1)
+        self.assertRaises(OverflowError, pollster.modify, 1, -1)
+        self.assertRaises(OverflowError, pollster.modify, 1, USHRT_MAX + 1)
+
 
 def test_main():
     run_unittest(DevPollTests)
diff -r e78743e03c8f Lib/test/test_poll.py
--- a/Lib/test/test_poll.py	Fri Dec 13 12:08:55 2013 +0200
+++ b/Lib/test/test_poll.py	Fri Dec 13 12:54:09 2013 +0200
@@ -4,7 +4,7 @@
 import subprocess
 import random
 import select
-import _testcapi
+from _testcapi import USHRT_MAX, INT_MAX, UINT_MAX
 try:
     import threading
 except ImportError:
@@ -161,10 +161,13 @@
         if x != 5:
             self.fail('Overflow must have occurred')
 
-        pollster = select.poll()
-        # Issue 15989
-        self.assertRaises(OverflowError, pollster.poll, _testcapi.INT_MAX + 1)
-        self.assertRaises(OverflowError, pollster.poll, _testcapi.UINT_MAX + 1)
+        # Issues #15989, #17919
+        self.assertRaises(OverflowError, pollster.register, 0, -1)
+        self.assertRaises(OverflowError, pollster.register, 0, USHRT_MAX + 1)
+        self.assertRaises(OverflowError, pollster.modify, 1, -1)
+        self.assertRaises(OverflowError, pollster.modify, 1, USHRT_MAX + 1)
+        self.assertRaises(OverflowError, pollster.poll, INT_MAX + 1)
+        self.assertRaises(OverflowError, pollster.poll, UINT_MAX + 1)
 
     @unittest.skipUnless(threading, 'Threading required for this test.')
     @reap_threads
diff -r e78743e03c8f Modules/selectmodule.c
--- a/Modules/selectmodule.c	Fri Dec 13 12:08:55 2013 +0200
+++ b/Modules/selectmodule.c	Fri Dec 13 12:54:09 2013 +0200
@@ -356,7 +356,7 @@
         assert(i < self->ufd_len);
         /* Never overflow */
         self->ufds[i].fd = (int)PyLong_AsLong(key);
-        self->ufds[i].events = (short)PyLong_AsLong(value);
+        self->ufds[i].events = (short)(unsigned short)PyLong_AsLong(value);
         i++;
     }
     assert(i == self->ufd_len);
@@ -364,6 +364,24 @@
     return 1;
 }
 
+static int
+ushort_converter(PyObject *obj, void *ptr)
+{
+    unsigned long uval;
+
+    uval = PyLong_AsUnsignedLong(obj);
+    if (uval == (unsigned long)-1 && PyErr_Occurred())
+        return 0;
+    if (uval > USHRT_MAX) {
+        PyErr_SetString(PyExc_OverflowError,
+                        "Python int too large for C unsigned int");
+        return 0;
+    }
+
+    *(unsigned short *)ptr = Py_SAFE_DOWNCAST(uval, unsigned long, unsigned short);
+    return 1;
+}
+
 PyDoc_STRVAR(poll_register_doc,
 "register(fd [, eventmask] ) -> None\n\n\
 Register a file descriptor with the polling object.\n\
@@ -375,10 +393,11 @@
 poll_register(pollObject *self, PyObject *args)
 {
     PyObject *o, *key, *value;
-    int fd, events = POLLIN | POLLPRI | POLLOUT;
+    int fd;
+    unsigned short events = POLLIN | POLLPRI | POLLOUT;
     int err;
 
-    if (!PyArg_ParseTuple(args, "O|i:register", &o, &events)) {
+    if (!PyArg_ParseTuple(args, "O|O&:register", &o, ushort_converter, &events)) {
         return NULL;
     }
 
@@ -418,10 +437,11 @@
 poll_modify(pollObject *self, PyObject *args)
 {
     PyObject *o, *key, *value;
-    int fd, events;
+    int fd;
+    unsigned short events;
     int err;
 
-    if (!PyArg_ParseTuple(args, "Oi:modify", &o, &events)) {
+    if (!PyArg_ParseTuple(args, "OO&:modify", &o, ushort_converter, &events)) {
         return NULL;
     }
 
@@ -728,12 +748,13 @@
 internal_devpoll_register(devpollObject *self, PyObject *args, int remove)
 {
     PyObject *o;
-    int fd, events = POLLIN | POLLPRI | POLLOUT;
+    int fd;
+    unsigned short events = POLLIN | POLLPRI | POLLOUT;
 
     if (self->fd_devpoll < 0)
         return devpoll_err_closed();
 
-    if (!PyArg_ParseTuple(args, "O|i:register", &o, &events)) {
+    if (!PyArg_ParseTuple(args, "O|O&:register", &o, ushort_converter, &events)) {
         return NULL;
     }
 
@@ -751,7 +772,7 @@
     }
 
     self->fds[self->n_fds].fd = fd;
-    self->fds[self->n_fds].events = events;
+    self->fds[self->n_fds].events = (signed short)events;
 
     if (++self->n_fds == self->max_n_fds) {
         if (devpoll_flush(self))