diff --git a/phpseclib/Crypt/AES.php b/phpseclib/Crypt/AES.php
index 07e975b8..94a08423 100644
--- a/phpseclib/Crypt/AES.php
+++ b/phpseclib/Crypt/AES.php
@@ -178,10 +178,7 @@ class Crypt_AES extends Crypt_Rijndael {
     {
         if ( !defined('CRYPT_AES_MODE') ) {
             switch (true) {
-                case extension_loaded('mcrypt'):
-                    // i'd check to see if aes was supported, by doing in_array('des', mcrypt_list_algorithms('')),
-                    // but since that can be changed after the object has been created, there doesn't seem to be
-                    // a lot of point...
+                case extension_loaded('mcrypt') && in_array('rijndael-128', mcrypt_list_algorithms()):
                     define('CRYPT_AES_MODE', CRYPT_AES_MODE_MCRYPT);
                     break;
                 default:
diff --git a/phpseclib/Crypt/DES.php b/phpseclib/Crypt/DES.php
index b8322507..c249d6b6 100644
--- a/phpseclib/Crypt/DES.php
+++ b/phpseclib/Crypt/DES.php
@@ -295,10 +295,7 @@ class Crypt_DES {
     {
         if ( !defined('CRYPT_DES_MODE') ) {
             switch (true) {
-                case extension_loaded('mcrypt'):
-                    // i'd check to see if des was supported, by doing in_array('des', mcrypt_list_algorithms('')),
-                    // but since that can be changed after the object has been created, there doesn't seem to be
-                    // a lot of point...
+                case extension_loaded('mcrypt') && in_array('des', mcrypt_list_algorithms()):
                     define('CRYPT_DES_MODE', CRYPT_DES_MODE_MCRYPT);
                     break;
                 default:
diff --git a/phpseclib/Crypt/RC4.php b/phpseclib/Crypt/RC4.php
index 0826362d..0eb1c2b5 100644
--- a/phpseclib/Crypt/RC4.php
+++ b/phpseclib/Crypt/RC4.php
@@ -142,15 +142,6 @@ class Crypt_RC4 {
      */
     var $decryptIndex = 0;
 
-    /**
-     * MCrypt parameters
-     *
-     * @see Crypt_RC4::setMCrypt()
-     * @var Array
-     * @access private
-     */
-    var $mcrypt = array('', '');
-
     /**
      * The Encryption Algorithm
      *
@@ -184,10 +175,7 @@ class Crypt_RC4 {
     {
         if ( !defined('CRYPT_RC4_MODE') ) {
             switch (true) {
-                case extension_loaded('mcrypt') && (defined('MCRYPT_ARCFOUR') || defined('MCRYPT_RC4')):
-                    // i'd check to see if rc4 was supported, by doing in_array('arcfour', mcrypt_list_algorithms('')),
-                    // but since that can be changed after the object has been created, there doesn't seem to be
-                    // a lot of point...
+                case extension_loaded('mcrypt') && (defined('MCRYPT_ARCFOUR') || defined('MCRYPT_RC4')) && in_array('arcfour', mcrypt_list_algorithms()):
                     define('CRYPT_RC4_MODE', CRYPT_RC4_MODE_MCRYPT);
                     break;
                 default:
@@ -323,24 +311,6 @@ class Crypt_RC4 {
     {
     }
 
-    /**
-     * Sets MCrypt parameters. (optional)
-     *
-     * If MCrypt is being used, empty strings will be used, unless otherwise specified.
-     *
-     * @link http://php.net/function.mcrypt-module-open#function.mcrypt-module-open
-     * @access public
-     * @param optional Integer $algorithm_directory
-     * @param optional Integer $mode_directory
-     */
-    function setMCrypt($algorithm_directory = '', $mode_directory = '')
-    {
-        if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {
-            $this->mcrypt = array($algorithm_directory, $mode_directory);
-            $this->_closeMCrypt();
-        }
-    }
-
     /**
      * Encrypts a message.
      *
diff --git a/phpseclib/Crypt/TripleDES.php b/phpseclib/Crypt/TripleDES.php
index adb2a309..9f4757ec 100644
--- a/phpseclib/Crypt/TripleDES.php
+++ b/phpseclib/Crypt/TripleDES.php
@@ -248,10 +248,7 @@ class Crypt_TripleDES {
     {
         if ( !defined('CRYPT_DES_MODE') ) {
             switch (true) {
-                case extension_loaded('mcrypt'):
-                    // i'd check to see if des was supported, by doing in_array('des', mcrypt_list_algorithms('')),
-                    // but since that can be changed after the object has been created, there doesn't seem to be
-                    // a lot of point...
+                case extension_loaded('mcrypt') && in_array('tripledes', mcrypt_list_algorithms()):
                     define('CRYPT_DES_MODE', CRYPT_DES_MODE_MCRYPT);
                     break;
                 default: