diff --git a/src/RegisteredDomain.php b/src/RegisteredDomain.php
index 922ec14..4a83d53 100644
--- a/src/RegisteredDomain.php
+++ b/src/RegisteredDomain.php
@@ -44,12 +44,118 @@ protected function normalizeHost($url)
         $parts = explode('.', $host);
         $utf8Host = '';
         foreach ($parts as $part) {
-            $utf8Host = $utf8Host . (($utf8Host === '') ? '' : '.') . idn_to_utf8($part);
+            $utf8Host = $utf8Host . (($utf8Host === '') ? '' : '.') . $this->convertPunycode($part);
         }
 
         return mb_strtolower($utf8Host);
     }
 
+    /**
+     * Convert a punycode string to UTF-8 if needed
+     *
+     * @param string $part host component
+     *
+     * @return string host component as UTF-8
+     */
+    protected function convertPunycode($part)
+    {
+        if (strpos($part,'xn--')===0) {
+            if (function_exists('idn_to_utf8')) {
+                $part = idn_to_utf8($part);
+            } else {
+                $part = $this->decodePunycode($part);
+            }
+        }
+        return $part;
+    }
+
+    /**
+     * convert punycode to UTF-8 (the hard way) Used only if idn_to_utf8() is not available
+     *
+     * This fallback adapted from https://ckon.wordpress.com/2010/08/24/punycode-to-unicode-converter-php/
+     *
+     * @param string $encoded
+     * @return string
+     */
+    protected function decodePunycode($encoded)
+    {
+        $prefix = 'xn--';
+        $safe_char = 0xFFFC;
+        $base = 36;
+        $tmin = 1;
+        $tmax = 26;
+        $skew = 38;
+        $damp = 700;
+
+        if (strpos($encoded, $prefix) !== 0 || strlen(trim(str_replace($prefix, '', $encoded))) == 0) {
+            return $encoded;
+        }
+
+        $is_first = true;
+        $bias = 72;
+        $idx = 0;
+        $char = 0x80;
+        $decoded = array();
+        $output = '';
+
+        $delim_pos = strrpos($encoded, '-');
+        if ($delim_pos > strlen($prefix)) {
+            for ($k = strlen($prefix); $k < $delim_pos; ++$k) {
+                $decoded[] = ord($encoded{$k});
+            }
+        }
+        $deco_len = count($decoded);
+        $enco_len = strlen($encoded);
+
+        for ($enco_idx = $delim_pos ? ($delim_pos + 1) : 0; $enco_idx < $enco_len; ++$deco_len) {
+            for ($old_idx = $idx, $w = 1, $k = $base; 1; $k += $base) {
+                $cp = ord($encoded{$enco_idx++});
+                $digit = ($cp - 48 < 10) ? $cp - 22 : (($cp - 65 < 26) ? $cp - 65 : (($cp - 97 < 26) ? $cp - 97 : $base));
+                $idx += $digit * $w;
+                $t = ($k <= $bias) ? $tmin : (($k >= $bias + $tmax) ? $tmax : ($k - $bias));
+                if ($digit < $t) {
+                    break;
+                }
+                $w = (int)($w * ($base - $t));
+            }
+            $delta = $idx - $old_idx;
+            $delta = intval($is_first ? ($delta / $damp) : ($delta / 2));
+            $delta += intval($delta / ($deco_len + 1));
+            for ($k = 0; $delta > (($base - $tmin) * $tmax) / 2; $k += $base) {
+                $delta = intval($delta / ($base - $tmin));
+            }
+            $bias = intval($k + ($base - $tmin + 1) * $delta / ($delta + $skew));
+            $is_first = false;
+            $char += (int)($idx / ($deco_len + 1));
+            $idx %= ($deco_len + 1);
+            if ($deco_len > 0) {
+                for ($i = $deco_len; $i > $idx; $i--) {
+                    $decoded[$i] = $decoded[($i - 1)];
+                }
+            }
+            $decoded[$idx++] = $char;
+        }
+
+        foreach ($decoded as $k => $v) {
+            if ($v < 128) {
+                $output .= chr($v);
+            } // 7bit are transferred literally
+            elseif ($v < (1 << 11)) {
+                $output .= chr(192 + ($v >> 6)) . chr(128 + ($v & 63));
+            } // 2 bytes
+            elseif ($v < (1 << 16)) {
+                $output .= chr(224 + ($v >> 12)) . chr(128 + (($v >> 6) & 63)) . chr(128 + ($v & 63));
+            } // 3 bytes
+            elseif ($v < (1 << 21)) {
+                $output .= chr(240 + ($v >> 18)) . chr(128 + (($v >> 12) & 63)) . chr(128 + (($v >> 6) & 63)) . chr(128 + ($v & 63));
+            } // 4 bytes
+            else {
+                $output .= $safe_char;
+            } //  'Conversion from UCS-4 to UTF-8 failed: malformed input at byte '.$k
+        }
+        return $output;
+    }
+
     /**
      * Determine the registered domain portion of the supplied host string
      *