diff --git a/phpseclib/Crypt/RSA.php b/phpseclib/Crypt/RSA.php
index bd2c77df..e931267d 100644
--- a/phpseclib/Crypt/RSA.php
+++ b/phpseclib/Crypt/RSA.php
@@ -201,6 +201,15 @@ class RSA extends AsymmetricKey
      */
     private $sLen;
 
+
+    /**
+     * Comment
+     *
+     * @var string
+     * @access private
+     */
+    private $comment;
+
     /**
      * Hash function for the Mask Generation Function
      *