diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 81c328c..1c3a345 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -458,7 +458,7 @@ function _theme($hook, $variables = array()) {
       // Only log a message when not trying theme suggestions ($hook being an
       // array).
       if (!isset($candidate)) {
-        \Drupal::logger('theme')->warning('Theme hook %hook not found.', array('%hook' => $hook));
+        trigger_error(String::format('Theme hook %hook not found.', array('%hook' => $hook)), E_USER_WARNING);
       }
       // There is no theme implementation for the hook passed. Return FALSE so
       // the function calling _theme() can differentiate between a hook that