diff --git a/phpBB/includes/template/filter.php b/phpBB/includes/template/filter.php
index 453e2a05ce..2706eb9040 100644
--- a/phpBB/includes/template/filter.php
+++ b/phpBB/includes/template/filter.php
@@ -878,15 +878,8 @@ class phpbb_template_filter extends php_user_filter
 		if (!preg_match('/^\w+$/', $tag_args))
 		{
 			// The hook location is wrongly formatted,
-			// if the `DEBUG` constant is set then trigger a warning,
-			// otherwise drop the hook and continue
-			if (defined('DEBUG'))
-			{
-				global $user;
-				trigger_error($user->lang('ERR_TEMPLATE_EVENT_LOCATION', $tag_args), E_USER_NOTICE);
-			}
-
-			return;
+			global $user;
+			trigger_error($user->lang('ERR_TEMPLATE_EVENT_LOCATION', $tag_args), E_USER_ERROR);
 		}
 		$location = $tag_args;