diff --git a/core/modules/user/templates/user.html.twig b/core/modules/user/templates/user.html.twig
index 2f6f640..f5bd2b6 100644
--- a/core/modules/user/templates/user.html.twig
+++ b/core/modules/user/templates/user.html.twig
@@ -23,7 +23,12 @@
  * @ingroup themeable
  */
 #}
-<article{{ attributes }}>
+{%
+  set classes = [
+    'profile',
+  ]
+%}
+<article{{ attributes.addClass(classes) }}>
   {% if content %}
     {{- content -}}
   {% endif %}
diff --git a/core/modules/user/templates/username.html.twig b/core/modules/user/templates/username.html.twig
index 5d4f2f7..06562c4 100644
--- a/core/modules/user/templates/username.html.twig
+++ b/core/modules/user/templates/username.html.twig
@@ -18,8 +18,13 @@
  * @ingroup themeable
  */
 #}
+{%
+  set classes = [
+    'username',
+  ]
+%}
 {% if link_path -%}
-  <a{{ attributes }}>{{ name }}{{ extra }}</a>
+  <a{{ attributes.addClass(classes) }}>{{ name }}{{ extra }}</a>
 {%- else -%}
   <span{{ attributes }}>{{ name }}{{ extra }}</span>
 {%- endif -%}
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 75777bb..49850f3 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -625,11 +625,7 @@ function template_preprocess_username(&$variables) {
     $variables['link_path'] = $account->homepage;
     $variables['homepage'] = $account->homepage;
   }
-  // Set a default class.
-  $variables['attributes']['class'] = array('username');
   // We have a link path, so we should generate a link using url().
-  // Additional classes may be added as array elements like
-  // $variables['attributes']['class'][] = 'myclass';
   if (isset($variables['link_path'])) {
     $variables['attributes']['href'] = url($variables['link_path'], $variables['link_options']);
   }
diff --git a/core/modules/user/user.pages.inc b/core/modules/user/user.pages.inc
index 4a09d7b..b548e3b 100644
--- a/core/modules/user/user.pages.inc
+++ b/core/modules/user/user.pages.inc
@@ -29,9 +29,6 @@ function template_preprocess_user(&$variables) {
   foreach (Element::children($variables['elements']) as $key) {
     $variables['content'][$key] = $variables['elements'][$key];
   }
-
-  // Set up attributes.
-  $variables['attributes']['class'][] = 'profile';
 }
 
 /**