Index: Modules/_fileio.c
===================================================================
--- Modules/_fileio.c	(revision 70632)
+++ Modules/_fileio.c	(working copy)
@@ -611,6 +611,7 @@
 		n = -1;
 
 	if (n < 0) {
+		Py_DECREF(bytes);
 		if (errno == EAGAIN)
 			Py_RETURN_NONE;
 		PyErr_SetFromErrno(PyExc_IOError);