diff -r 527b77a63cc9 asyncio/selectors.py
--- a/asyncio/selectors.py	Fri Jan 09 15:38:48 2015 +0100
+++ b/asyncio/selectors.py	Mon Jan 12 11:09:44 2015 +0100
@@ -176,7 +176,7 @@
         mapping = self.get_map()
         try:
             return mapping[fileobj]
-        except KeyError:
+        except (KeyError, TypeError):
             raise KeyError("{!r} is not registered".format(fileobj)) from None

     @abstractmethod
@@ -256,6 +256,7 @@

     def close(self):
         self._fd_to_key.clear()
+        self._map = None

     def get_map(self):
         return self._map