diff --git a/phpseclib/Crypt/RSA.php b/phpseclib/Crypt/RSA.php
index 4ef58dad..da9df9f4 100644
--- a/phpseclib/Crypt/RSA.php
+++ b/phpseclib/Crypt/RSA.php
@@ -1333,9 +1333,14 @@ class RSA
                 xml_set_character_data_handler($xml, '_data_handler');
                 // add <xml></xml> to account for "dangling" tags like <BitStrength>...</BitStrength> that are sometimes added
                 if (!xml_parse($xml, '<xml>' . $key . '</xml>')) {
+                    xml_parser_free($xml);
+                    unset($xml);
                     return false;
                 }
 
+                xml_parser_free($xml);
+                unset($xml);
+
                 return isset($this->components['modulus']) && isset($this->components['publicExponent']) ? $this->components : false;
             // from PuTTY's SSHPUBK.C
             case self::PRIVATE_FORMAT_PUTTY: