diff --git a/library/HTMLPurifier/AttrDef/URI/Host.php b/library/HTMLPurifier/AttrDef/URI/Host.php
index 17a97c1ec..8057a2022 100644
--- a/library/HTMLPurifier/AttrDef/URI/Host.php
+++ b/library/HTMLPurifier/AttrDef/URI/Host.php
@@ -90,17 +90,13 @@ public function validate($string, $config, $context)
         }
 
         // PHP 5.3 and later support this functionality natively
-        if (function_exists('idn_to_ascii')) {
-            if (defined('IDNA_NONTRANSITIONAL_TO_ASCII') && defined('INTL_IDNA_VARIANT_UTS46')) {
-                $string = idn_to_ascii($string, IDNA_NONTRANSITIONAL_TO_ASCII, INTL_IDNA_VARIANT_UTS46);
-            } else {
-                $string = idn_to_ascii($string);
-            }
+        if (\function_exists('idn_to_ascii')) {
+            $string = idn_to_ascii($string, IDNA_NONTRANSITIONAL_TO_ASCII, INTL_IDNA_VARIANT_UTS46);
 
         // If we have Net_IDNA2 support, we can support IRIs by
         // punycoding them. (This is the most portable thing to do,
         // since otherwise we have to assume browsers support
-        } elseif ($config->get('Core.EnableIDNA') && class_exists('Net_IDNA2')) {
+        } elseif (class_exists('Net_IDNA2') && $config->get('Core.EnableIDNA') ) {
             $idna = new Net_IDNA2(array('encoding' => 'utf8', 'overlong' => false, 'strict' => true));
             // we need to encode each period separately
             $parts = explode('.', $string);
diff --git a/library/HTMLPurifier/Bootstrap.php b/library/HTMLPurifier/Bootstrap.php
index 8805eccff..ba68076cf 100644
--- a/library/HTMLPurifier/Bootstrap.php
+++ b/library/HTMLPurifier/Bootstrap.php
@@ -5,21 +5,6 @@
     define('HTMLPURIFIER_PREFIX', realpath(dirname(__FILE__) . '/..'));
 }
 
-// accommodations for versions earlier than 5.0.2
-// borrowed from PHP_Compat, LGPL licensed, by Aidan Lister <aidan@php.net>
-if (!defined('PHP_EOL')) {
-    switch (strtoupper(substr(PHP_OS, 0, 3))) {
-        case 'WIN':
-            define('PHP_EOL', "\r\n");
-            break;
-        case 'DAR':
-            define('PHP_EOL', "\r");
-            break;
-        default:
-            define('PHP_EOL', "\n");
-    }
-}
-
 /**
  * Bootstrap class that contains meta-functionality for HTML Purifier such as
  * the autoload function.
diff --git a/library/HTMLPurifier/Printer.php b/library/HTMLPurifier/Printer.php
index 549e4cea1..e7b5c7256 100644
--- a/library/HTMLPurifier/Printer.php
+++ b/library/HTMLPurifier/Printer.php
@@ -169,14 +169,7 @@ protected function listify($array, $polite = false)
      */
     protected function getClass($obj, $sec_prefix = '')
     {
-        static $five = null;
-        if ($five === null) {
-            $five = version_compare(PHP_VERSION, '5', '>=');
-        }
         $prefix = 'HTMLPurifier_' . $sec_prefix;
-        if (!$five) {
-            $prefix = strtolower($prefix);
-        }
         $class = str_replace($prefix, '', get_class($obj));
         $lclass = strtolower($class);
         $class .= '(';
diff --git a/tests/HTMLPurifier/PHPT/ze1_compatibility_mode.phpt b/tests/HTMLPurifier/PHPT/ze1_compatibility_mode.phpt
deleted file mode 100644
index 606d7592e..000000000
--- a/tests/HTMLPurifier/PHPT/ze1_compatibility_mode.phpt
+++ /dev/null
@@ -1,14 +0,0 @@
---TEST--
-Error with zend.ze1_compatibility_mode test
---PRESKIPIF--
-<?php
-if (version_compare(PHP_VERSION, '5.3.0') >= 0) {
-    echo 'skip - ze1_compatibility_mode not present in PHP 5.3 or later';
-}
---INI--
-zend.ze1_compatibility_mode = 1
---FILE--
-<?php
-require '../library/HTMLPurifier.auto.php';
---EXPECTF--
-Fatal error: HTML Purifier is not compatible with zend.ze1_compatibility_mode; please turn it off in %s