diff --git a/phpBB/includes/ucp/ucp_pm_compose.php b/phpBB/includes/ucp/ucp_pm_compose.php
index 2b8468590e..f35812b90a 100644
--- a/phpBB/includes/ucp/ucp_pm_compose.php
+++ b/phpBB/includes/ucp/ucp_pm_compose.php
@@ -1173,7 +1173,7 @@ function compose_pm($id, $mode, $action, $user_folders = array())
break;
}
- $s_hidden_fields .= (isset($check_value)) ? '' : '';
+ $s_hidden_fields = (isset($check_value)) ? '' : '';
$s_hidden_fields .= ($draft_id || isset($_REQUEST['draft_loaded'])) ? '' : '';
$form_enctype = (@ini_get('file_uploads') == '0' || strtolower(@ini_get('file_uploads')) == 'off' || !$config['allow_pm_attach'] || !$auth->acl_get('u_pm_attach')) ? '' : ' enctype="multipart/form-data"';