diff --git a/src/Exception/ServerErrorException.php b/src/Exception/ServerErrorException.php
index e524c520..bdcec4dc 100644
--- a/src/Exception/ServerErrorException.php
+++ b/src/Exception/ServerErrorException.php
@@ -29,10 +29,10 @@ class ServerErrorException extends OAuthException
     /**
      * {@inheritdoc}
      */
-    public function __construct(
-        $parameter = 'The authorization server encountered an unexpected condition which prevented it from fulfilling'
-        . 'the request.'
-    ) {
+    public function __construct($parameter = null)
+    {
+        $parameter = is_null($parameter) ? 'The authorization server encountered an unexpected condition which prevented
+         it from fulfilling the request.' : $parameter;
         parent::__construct($parameter);
     }
 }