Index: Objects/longobject.c
===================================================================
--- Objects/longobject.c	(revision 65155)
+++ Objects/longobject.c	(working copy)
@@ -178,7 +178,9 @@
 		return NULL;
 	}
 	if (Py_IS_NAN(dval)) {
-		return PyLong_FromLong(0L);
+		PyErr_SetString(PyExc_ValueError,
+			"cannot convert float NaN to long");
+		return NULL;
 	}
 	if (dval < 0.0) {
 		neg = 1;
Index: Lib/test/test_long.py
===================================================================
--- Lib/test/test_long.py	(revision 65155)
+++ Lib/test/test_long.py	(working copy)
@@ -745,7 +745,8 @@
 
     def test_nan_inf(self):
         self.assertRaises(OverflowError, long, float('inf'))
-        self.assertEqual(long(float('nan')), 0L)
+        self.assertRaises(OverflowError, long, float('-inf'))
+        self.assertRaises(ValueError, long, float('nan'))
 
 def test_main():
     test_support.run_unittest(LongTest)