Index: Objects/unicodeobject.c
===================================================================
--- Objects/unicodeobject.c	(revision 77001)
+++ Objects/unicodeobject.c	(working copy)
@@ -1638,7 +1638,7 @@
          size = PyByteArray_GET_SIZE(output);
          data = PyByteArray_AS_STRING(output);
     }
-    if (size != strlen(data)) {
+    if (size && (size != strlen(data))) {
         PyErr_SetString(PyExc_TypeError, "embedded NUL character");
         Py_DECREF(output);
         return 0;
Index: Modules/posixmodule.c
===================================================================
--- Modules/posixmodule.c	(revision 77001)
+++ Modules/posixmodule.c	(working copy)
@@ -555,17 +555,20 @@
 
 /* Convert a bytes object to a char*. Optionally lock the buffer if it is a
    bytes array. */
+static char _null_char = 0;
 
 static char*
 bytes2str(PyObject* o, int lock)
 {
+	char *rv;
 	if(PyBytes_Check(o))
 		return PyBytes_AsString(o);
 	else if(PyByteArray_Check(o)) {
 		if (lock && PyObject_GetBuffer(o, NULL, 0) < 0)
 			/* On a bytearray, this should not fail. */
 			PyErr_BadInternalCall();
-		return PyByteArray_AsString(o);
+		rv = PyByteArray_AsString(o);
+		return rv ? rv : &_null_char;
 	} else {
 		/* The FS converter should have verified that this
 		   is either bytes or bytearray. */
@@ -580,7 +583,7 @@
 release_bytes(PyObject* o)
 {
 	if (PyByteArray_Check(o))
-		o->ob_type->tp_as_buffer->bf_releasebuffer(NULL, 0);
+		o->ob_type->tp_as_buffer->bf_releasebuffer(o, 0);
 	Py_DECREF(o);
 }