diff --git a/library/HTMLPurifier/AttrDef/URI/Host.php b/library/HTMLPurifier/AttrDef/URI/Host.php
index e7df800b..371f228a 100644
--- a/library/HTMLPurifier/AttrDef/URI/Host.php
+++ b/library/HTMLPurifier/AttrDef/URI/Host.php
@@ -89,11 +89,14 @@ class HTMLPurifier_AttrDef_URI_Host extends HTMLPurifier_AttrDef
             return $string;
         }
 
+        // PHP 5.3 and later support this functionality natively
+        if (function_exists('idn_to_ascii')) {
+            return idn_to_ascii($string);
+
         // If we have Net_IDNA2 support, we can support IRIs by
         // punycoding them. (This is the most portable thing to do,
         // since otherwise we have to assume browsers support
-
-        if ($config->get('Core.EnableIDNA')) {
+        } elseif ($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/tests/HTMLPurifier/AttrDef/URI/HostTest.php b/tests/HTMLPurifier/AttrDef/URI/HostTest.php
index 00e56ed4..b645aa4c 100644
--- a/tests/HTMLPurifier/AttrDef/URI/HostTest.php
+++ b/tests/HTMLPurifier/AttrDef/URI/HostTest.php
@@ -42,7 +42,7 @@ class HTMLPurifier_AttrDef_URI_HostTest extends HTMLPurifier_AttrDefHarness
 
     public function testIDNA()
     {
-        if (!$GLOBALS['HTMLPurifierTest']['Net_IDNA2']) {
+        if (!$GLOBALS['HTMLPurifierTest']['Net_IDNA2'] && !function_exists("idn_to_ascii")) {
             return false;
         }
         $this->config->set('Core.EnableIDNA', true);