Index: wp-admin/themes.php
===================================================================
--- wp-admin/themes.php (revision 10768)
+++ wp-admin/themes.php (working copy)
@@ -180,7 +180,7 @@
        $author = $themes[$theme_name]['Author'];
        $screenshot = $themes[$theme_name]['Screenshot'];
        $stylesheet_dir = $themes[$theme_name]['Stylesheet Dir'];
-       $preview_link = clean_url( get_option('home') . '/');
+       $preview_link = clean_url( get_option('siteurl') . '/');
        $preview_link = htmlspecialchars( add_query_arg( array('preview' => 1, 'template' => $template, 'stylesheet' => $stylesheet, 'TB_iframe' => 'true', 'width' => 600, 'height' => 400 ), $preview_link ) );
        $preview_text = attribute_escape( sprintf( __('Preview of "%s"'), $title ) );
        $tags = $themes[$theme_name]['Tags'];