diff --git a/lib/base.php b/lib/base.php
index 0f55c1175c7ded58e1380c02413c17e1903fa4a3..37008b5a351baf13d085805c2f9b8a67a54d68c2 100644
--- a/lib/base.php
+++ b/lib/base.php
@@ -721,7 +721,7 @@ class OC {
 			header('Status: 400 Bad Request');
 			OC_Template::printErrorPage(
 				$l->t('You are accessing the server from an untrusted domain.'),
-				$l->t('Please contact your administrator')
+				$l->t('Please contact your administrator. If you are an administrator of this instance, configure the "trusted_domain" setting in config/config.php. An example configuration is provided in config/config.sample.php.')
 			);
 			return;
 		}