Index: mu-plugins/wp-super-cache/wp-cache-phase2.php
===================================================================
--- mu-plugins/wp-super-cache/wp-cache-phase2.php	(revision 60)
+++ mu-plugins/wp-super-cache/wp-cache-phase2.php	(working copy)
@@ -1,5 +1,7 @@
 <?php
 
+$_SERVER['REQUEST_URI_ORI'] = $_SERVER['REQUEST_URI'];
+
 function wp_cache_phase2() {
 	global $cache_filename, $cache_acceptable_files, $wp_cache_gzip_encoding, $super_cache_enabled, $cache_rebuild_files, $wp_cache_gmt_offset, $wp_cache_blog_charset, $wp_cache_last_gc;
 	global $cache_max_time, $wp_cache_not_logged_in;
@@ -183,8 +185,10 @@
 }
 
 function get_current_url_supercache_dir() {
-	global $cached_direct_pages, $cache_path;
-	$uri = preg_replace('/[ <>\'\"\r\n\t\(\)]/', '', str_replace( '/index.php', '/', str_replace( '..', '', preg_replace("/(\?.*)?$/", '', $_SERVER['REQUEST_URI'] ) ) ) );
+	global $cached_direct_pages, $cache_path, $uri;
+
+	$uri = (empty($_SERVER['REQUEST_URI_ORI']) ? $_SERVER['REQUEST_URI'] : $_SERVER['REQUEST_URI_ORI']);
+	$uri = preg_replace('/[ <>\'\"\r\n\t\(\)]/', '', str_replace( '/index.php', '/', str_replace( '..', '', preg_replace("/(\?.*)?$/", '', $uri ) ) ) );
 	$uri = str_replace( '\\', '', $uri );
 	$dir = strtolower(preg_replace('/:.*$/', '',  $_SERVER["HTTP_HOST"])) . $uri; // To avoid XSS attacks
 	$dir = apply_filters( 'supercache_dir', $dir );