diff -r 07cfe9f5561b Doc/library/selectors.rst
--- a/Doc/library/selectors.rst	Fri Dec 06 12:57:40 2013 -0800
+++ b/Doc/library/selectors.rst	Fri Dec 06 14:00:43 2013 -0800
@@ -102,7 +102,8 @@
 
       Register a file object for selection, monitoring it for I/O events.
 
-      *fileobj* is the file object to monitor.
+      *fileobj* is the file object to monitor.  It may either be an integer
+      file descriptor or an object with a ``fileno()`` method.
       *events* is a bitwise mask of events to monitor.
       *data* is an opaque object.
 
@@ -118,7 +119,9 @@
       *fileobj* must be a file object previously registered.
 
       This returns the associated :class:`SelectorKey` instance, or raises a
-      :exc:`KeyError` if the file object is not registered.
+      :exc:`KeyError` if *fileobj* is not registered.  It will raise
+      :exc:`ValueError` if *fileobj* is an object with a ``fileno()`` method
+      that has been closed.
 
    .. method:: modify(fileobj, events, data=None)
 
diff -r 07cfe9f5561b Lib/selectors.py
--- a/Lib/selectors.py	Fri Dec 06 12:57:40 2013 -0800
+++ b/Lib/selectors.py	Fri Dec 06 14:00:43 2013 -0800
@@ -89,6 +89,15 @@
 
         Returns:
         SelectorKey instance
+
+        Raises:
+        ValueError if events is invalid
+        KeyError if fileobj is already registered
+        OSError if fileobj is closed or otherwise is unacceptable to
+                the underlying system call (if a system call is made)
+
+        Note:
+        OSError may or may not be raised
         """
         raise NotImplementedError
 
@@ -101,6 +110,13 @@
 
         Returns:
         SelectorKey instance
+
+        Raises:
+        KeyError if fileobj is not registered
+
+        Note:
+        If fileobj is registered but has since been closed this does
+        *not* raise OSError (even if the wrapped syscall does)
         """
         raise NotImplementedError
 
@@ -114,6 +130,9 @@
 
         Returns:
         SelectorKey instance
+
+        Raises:
+        Anything that unregister() or register() raises
         """
         self.unregister(fileobj)
         return self.register(fileobj, events, data)
@@ -409,11 +428,20 @@
             if key.events & EVENT_READ:
                 kev = select.kevent(key.fd, select.KQ_FILTER_READ,
                                     select.KQ_EV_DELETE)
-                self._kqueue.control([kev], 0, 0)
+                try:
+                    self._kqueue.control([kev], 0, 0)
+                except OSError:
+                    # This can happen if the FD was closed since it
+                    # was registered.
+                    pass
             if key.events & EVENT_WRITE:
                 kev = select.kevent(key.fd, select.KQ_FILTER_WRITE,
                                     select.KQ_EV_DELETE)
-                self._kqueue.control([kev], 0, 0)
+                try:
+                    self._kqueue.control([kev], 0, 0)
+                except OSError:
+                    # See comment above.
+                    pass
             return key
 
         def select(self, timeout=None):
diff -r 07cfe9f5561b Lib/test/test_selectors.py
--- a/Lib/test/test_selectors.py	Fri Dec 06 12:57:40 2013 -0800
+++ b/Lib/test/test_selectors.py	Fri Dec 06 14:00:43 2013 -0800
@@ -94,6 +94,20 @@
         # unregister twice
         self.assertRaises(KeyError, s.unregister, rd)
 
+    def test_unregister_after_fd_close(self):
+        s = self.SELECTOR()
+        self.addCleanup(s.close)
+        rd, wr = socketpair()
+        r, w = rd.fileno(), wr.fileno()
+        self.addCleanup(rd.close)
+        self.addCleanup(wr.close)
+        s.register(r, selectors.EVENT_READ)
+        s.register(w, selectors.EVENT_WRITE)
+        rd.close()
+        wr.close()
+        s.unregister(r)
+        s.unregister(w)
+
     def test_modify(self):
         s = self.SELECTOR()
         self.addCleanup(s.close)