diff --git a/inc/class.page.php b/inc/class.page.php
--- a/inc/class.page.php
+++ b/inc/class.page.php
@@ -120,8 +120,8 @@ class page
 
    /* Compliant browsers which care, such as gecko, explicitly request xhtml: */
    if(!empty($_SERVER['HTTP_ACCEPT'])
-      && strpos($_SERVER['HTTP_ACCEPT'], 'application/xhtml+xml') !== FALSE
-      || !strlen($_SERVER['HTTP_ACCEPT']) /* then the browser doesn't care :-) */)
+      && (strpos($_SERVER['HTTP_ACCEPT'], 'application/xhtml+xml') !== FALSE
+	  || !strlen($_SERVER['HTTP_ACCEPT'])) /* then the browser doesn't care :-) */)
      {
        $this->xhtml = TRUE;
        header('Content-Type: application/xhtml+xml; charset=utf-8');