diff --git a/lib/classes/idna/ext/IdnaConvert.php b/lib/classes/idna/ext/IdnaConvert.php
index 868ac2a3..3c1b45c5 100644
--- a/lib/classes/idna/ext/IdnaConvert.php
+++ b/lib/classes/idna/ext/IdnaConvert.php
@@ -54,12 +54,10 @@ namespace Mso\IdnaConvert;
 
 class IdnaConvert {
 
-    const Version = '1.0.2';
+    const Version = '1.1.0';
     const SubVersion = 'main';
 
     // Internal settings, do not touch!
-    const PunycodePrefix = 'xn--';
-
     protected $encoding = 'utf8';          // Default input charset is UTF-8
     protected $strictMode = false;         // Behave strict or not
     protected $idnVersion = '2008';          // Can be either 2003 (old) or 2008 (default)
@@ -203,21 +201,17 @@ class IdnaConvert {
             list ($email_pref, $input) = explode('@', $input, 2);
             $arr = explode('.', $input);
             foreach ($arr as $k => $v) {
-                if (preg_match('!^' . preg_quote(self::PunycodePrefix, '!') . '!', $v)) {
-                    $conv = $punyCode->decode($v);
-                    if ($conv) {
-                        $arr[$k] = $conv;
-                    }
+                $conv = $punyCode->decode($v);
+                if ($conv) {
+                    $arr[$k] = $conv;
                 }
             }
             $input = join('.', $arr);
             $arr = explode('.', $email_pref);
             foreach ($arr as $k => $v) {
-                if (preg_match('!^' . preg_quote(self::PunycodePrefix, '!') . '!', $v)) {
-                    $conv = $punyCode->decode($v);
-                    if ($conv) {
-                        $arr[$k] = $conv;
-                    }
+                $conv = $punyCode->decode($v);
+                if ($conv) {
+                    $arr[$k] = $conv;
                 }
             }
             $email_pref = join('.', $arr);
@@ -248,7 +242,9 @@ class IdnaConvert {
                 $arr = explode('.', $input);
                 foreach ($arr as $k => $v) {
                     $conv = $punyCode->decode($v);
-                    $arr[$k] = ($conv) ? $conv : $v;
+                    if ($conv) {
+                        $arr[$k] = $conv;
+                    }
                 }
                 $return = join('.', $arr);
             }
diff --git a/lib/classes/idna/ext/Punycode.php b/lib/classes/idna/ext/Punycode.php
index 14a57f1c..781466b2 100644
--- a/lib/classes/idna/ext/Punycode.php
+++ b/lib/classes/idna/ext/Punycode.php
@@ -77,11 +77,32 @@ class Punycode implements PunycodeInterface
         $this->UnicodeTranscoder = $UnicodeTranscoder;
     }
 
+    /**
+     * Returns the used prefix for punycode-encoded strings
+     * @return string
+     */
     public function getPunycodePrefix()
     {
         return self::punycodePrefix;
     }
 
+    /**
+     * Checks, whether or not the provided string is a valid punycode string
+     * @param string $encoded
+     * @return boolean
+     */
+    public function validate($encoded) {
+        // Check for existence of the prefix
+        if (strpos($encoded, self::punycodePrefix) !== 0) {
+            return false;
+        }
+        // If nothing is left after the prefix, it is hopeless
+        if (strlen(trim($encoded)) <= strlen(self::punycodePrefix)) {
+            return false;
+        }
+        return true;
+    }
+
     /**
      * The actual decoding algorithm
      * @param string
@@ -89,19 +110,11 @@ class Punycode implements PunycodeInterface
      */
     public function decode($encoded)
     {
-        $decoded = [];
-        // find the Punycode prefix
-        if (!preg_match('!^' . preg_quote(self::punycodePrefix, '!') . '!', $encoded)) {
-        	// *** froxlor patch ***
-        	return $encoded;
-        	// *** end froxlor patch ***
-            throw new \InvalidArgumentException('This is not a punycode string');
-        }
-        $encode_test = preg_replace('!^' . preg_quote(self::punycodePrefix, '!') . '!', '', $encoded);
-        // If nothing left after removing the prefix, it is hopeless
-        if (!$encode_test) {
+        if (!$this->validate($encoded)) {
             return false;
         }
+
+        $decoded = [];
         // Find last occurence of the delimiter
         $delim_pos = strrpos($encoded, '-');
         if ($delim_pos > self::byteLength(self::punycodePrefix)) {