Index: src/wp-admin/includes/file.php
===================================================================
--- src/wp-admin/includes/file.php	(revision 25372)
+++ src/wp-admin/includes/file.php	(working copy)
@@ -802,9 +802,9 @@
 
 	// Set the permission constants if not already set.
 	if ( ! defined('FS_CHMOD_DIR') )
-		define('FS_CHMOD_DIR', 0755 );
+		define('FS_CHMOD_DIR', ( fileperms( ABSPATH . WPINC ) & 0777 ) | 0640 );
 	if ( ! defined('FS_CHMOD_FILE') )
-		define('FS_CHMOD_FILE', 0644 );
+		define('FS_CHMOD_FILE', ( fileperms( ABSPATH . 'wp-load.php' ) & 0777 ) | 0640 );
 
 	return true;
 }