diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index 0ee6f4c..8ec53d9 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -699,6 +699,7 @@ function template_preprocess_comment(&$variables) {
   );
   $variables['author'] = drupal_render($username);
   $variables['author_id'] = $comment->getOwnerId();
+  $variables['author_anonymous'] = $comment->getOwner()->isAnonymous();
   $variables['new_indicator_timestamp'] = $comment->getChangedTime();
   $variables['created'] = format_date($comment->getCreatedTime());
   // Avoid calling format_date() twice on the same timestamp.
diff --git a/core/modules/comment/templates/comment.html.twig b/core/modules/comment/templates/comment.html.twig
index 24dbd07..1da2a3b 100644
--- a/core/modules/comment/templates/comment.html.twig
+++ b/core/modules/comment/templates/comment.html.twig
@@ -70,7 +70,7 @@
   set classes = [
     'comment',
     status != 'published' ? status,
-    not author_id ? 'by-anonymous',
+    author_anonymous ? 'by-anonymous',
     author_id and author_id == commented_entity.getOwnerId() ? 'by-' ~ commented_entity.getEntityTypeId() ~ '-author',
     'clearfix',
   ]
diff --git a/core/themes/bartik/templates/comment.html.twig b/core/themes/bartik/templates/comment.html.twig
index 0fa1991..92e7a82 100644
--- a/core/themes/bartik/templates/comment.html.twig
+++ b/core/themes/bartik/templates/comment.html.twig
@@ -68,7 +68,7 @@
   set classes = [
     'comment',
     status != 'published' ? status,
-    not author_id ? 'by-anonymous',
+    author_anonymous ? 'by-anonymous',
     author_id and author_id == commented_entity.getOwnerId() ? 'by-' ~ commented_entity.getEntityTypeId() ~ '-author',
     'clearfix',
   ]