diff --git a/object-cache.php b/object-cache.php
index dd2ff80..eb43cea 100644
--- a/object-cache.php
+++ b/object-cache.php
@@ -12,8 +12,15 @@
 
 // Users with setups where multiple installs share a common wp-config.php or $table_prefix
 // can use this to guarantee uniqueness for the keys generated by this object cache
+// If WP_CACHE_KEY_SALT is not set, generate a key from DB parameters and blog id
 if ( ! defined( 'WP_CACHE_KEY_SALT' ) ) {
-	define( 'WP_CACHE_KEY_SALT', '' );
+	if ( defined('DB_NAME') && defined('DB_USER') && defined('DB_PASSWORD') && defined('DB_HOST')) {
+		global $blog_id, $table_prefix;
+		define( 'WP_CACHE_KEY_SALT', md5( DB_NAME . ":" . DB_USER . ":" . DB_PASSWORD . ":" . DB_HOST . ":" . $table_prefix . ":" . $blog_id ) );
+	}
+	else {
+		define( 'WP_CACHE_KEY_SALT', '' );
+	}
 }
 
 function wp_cache_add( $key, $data, $group = '', $expire = 0 ) {