diff --git a/wp-cache-base.php b/wp-cache-base.php
index 812601e3..df65196c 100644
--- a/wp-cache-base.php
+++ b/wp-cache-base.php
@@ -1,8 +1,9 @@
 <?php
-global $WPSC_HTTP_HOST, $blogcacheid;
+global $WPSC_HTTP_HOST, $cache_enabled, $cache_path, $blogcacheid, $blog_cache_dir;
 
 if ( ! empty( $_SERVER['HTTP_HOST'] ) ) {
-	$WPSC_HTTP_HOST = htmlentities( $_SERVER['HTTP_HOST'] );
+	$WPSC_HTTP_HOST = function_exists( 'mb_strtolower' ) ? mb_strtolower( $_SERVER['HTTP_HOST'] ) : strtolower( $_SERVER['HTTP_HOST'] );
+	$WPSC_HTTP_HOST = htmlentities( $WPSC_HTTP_HOST );
 } elseif ( PHP_SAPI === 'cli' && function_exists( 'get_option' ) ) {
 	$WPSC_HTTP_HOST = (string) parse_url( get_option( 'home' ), PHP_URL_HOST );
 } else {
@@ -11,29 +12,36 @@
 }
 
 // We want to be able to identify each blog in a WordPress MU install
-$blogcacheid = '';
+$blogcacheid    = '';
+$blog_cache_dir = $cache_path;
+
 if ( is_multisite() ) {
-	$blogcacheid = 'blog'; // main blog
-	if ( ( defined('SUBDOMAIN_INSTALL') && SUBDOMAIN_INSTALL ) || ( defined( 'VHOST' ) && VHOST == 'yes' ) ) {
+	global $current_blog;
+
+	if ( is_object( $current_blog ) && function_exists( 'is_subdomain_install' ) ) {
+		$blogcacheid = is_subdomain_install() ? $current_blog->domain : trim( $current_blog->path, '/' );
+	} elseif ( ( defined( 'SUBDOMAIN_INSTALL' ) && SUBDOMAIN_INSTALL ) || ( defined( 'VHOST' ) && VHOST === 'yes' ) ) {
 		$blogcacheid = $WPSC_HTTP_HOST;
 	} else {
-		if ( isset( $base ) == false ) {
-			$base = '';
-		}
 		$request_uri = str_replace( '..', '', preg_replace( '/[ <>\'\"\r\n\t\(\)]/', '', $_SERVER['REQUEST_URI'] ) );
-		if ( strlen( $request_uri ) > 0 && strpos( $request_uri, '/', 1 ) ) {
-			if ( $base == '/' ) {
-				$blogcacheid = substr( $request_uri, 1, strpos( $request_uri, '/', 1 ) - 1 );
-			} else {
-				$blogcacheid = str_replace( $base, '', $request_uri );
-				if ( $blogcacheid != '' ) {
-					$blogcacheid = substr( $blogcacheid, 0, strpos( $blogcacheid, '/', 1 ) );
-				}
-			}
-			if ( '/' == substr( $blogcacheid, -1 ) ) {
-				$blogcacheid = substr( $blogcacheid, 0, -1 );
-			}
+		$request_uri = str_replace( '//', '/', $request_uri );
+
+		$wpsc_path_segs  = array_filter( explode( '/', trim( $request_uri, '/' ) ) );
+		$wpsc_base_count = defined( 'PATH_CURRENT_SITE' ) ? count( array_filter( explode( '/', trim( PATH_CURRENT_SITE, '/' ) ) ) ) : 0;
+		if ( '/' !== substr( $request_uri, -1 ) ) {
+			$wpsc_path_segs = array_slice( $wpsc_path_segs, 0, -1 );
 		}
-		$blogcacheid = str_replace( '/', '', $blogcacheid );
+
+		if ( count( $wpsc_path_segs ) > $wpsc_base_count &&
+			( ! defined( 'PATH_CURRENT_SITE' ) || 0 === strpos( $request_uri, PATH_CURRENT_SITE ) )
+		) {
+			$blogcacheid = $wpsc_path_segs[ $wpsc_base_count ];
+		}
+	}
+
+	// If blogcacheid is empty then set it to main blog.
+	if ( empty( $blogcacheid ) ) {
+		$blogcacheid = 'blog';
 	}
+	$blog_cache_dir = str_replace( '//', '/', $cache_path . 'blogs/' . $blogcacheid . '/' );
 }
diff --git a/wp-cache-phase2.php b/wp-cache-phase2.php
index 41fb0c66..efc73e93 100644
--- a/wp-cache-phase2.php
+++ b/wp-cache-phase2.php
@@ -825,7 +825,7 @@ function get_oc_key( $url = false ) {
 	global $wp_cache_gzip_encoding, $WPSC_HTTP_HOST;
 
 	if ( $url ) {
-		$key = intval( $_SERVER[ 'SERVER_PORT' ] ) . strtolower( preg_replace( '/:.*$/', '',  $WPSC_HTTP_HOST ) ) . $url;
+		$key = intval( $_SERVER[ 'SERVER_PORT' ] ) . preg_replace( '/:.*$/', '',  $WPSC_HTTP_HOST ) . $url;
 	} else {
 		$key = get_current_url_supercache_dir();
 	}