diff --git a/phpseclib/File/ASN1.php b/phpseclib/File/ASN1.php
index fb2d6448..22e4d965 100644
--- a/phpseclib/File/ASN1.php
+++ b/phpseclib/File/ASN1.php
@@ -143,6 +143,16 @@ class ASN1
      */
     var $filters;
 
+    /**
+     * Current Location of most recent ASN.1 encode process
+     *
+     * Useful for debug purposes
+     *
+     * @var array
+     * @see self::encode_der()
+     */
+    var $location;
+
     /**
      * Type mapping table for the ANY type.
      *