Index: wp-content/index.php
===================================================================
--- wp-content/index.php	(revision 18407)
+++ wp-content/index.php	(working copy)
@@ -1,3 +1,3 @@
 <?php
-// Silence is golden.
+header('HTTP/1.0 404 Not Found'); // Silence is golden.
 ?>
\ No newline at end of file
Index: wp-content/plugins/index.php
===================================================================
--- wp-content/plugins/index.php	(revision 18407)
+++ wp-content/plugins/index.php	(working copy)
@@ -1,3 +1,3 @@
 <?php
-// Silence is golden.
+header('HTTP/1.0 404 Not Found'); // Silence is golden.
 ?>
\ No newline at end of file