diff -u b/core/modules/views/templates/views-view-summary-unformatted.html.twig b/core/modules/views/templates/views-view-summary-unformatted.html.twig
--- b/core/modules/views/templates/views-view-summary-unformatted.html.twig
+++ b/core/modules/views/templates/views-view-summary-unformatted.html.twig
@@ -21,16 +21,14 @@
  */
 #}
 {% for row in rows  %}
-  {%
-    set row_classes = [
-      row.active ? 'active',
-    ]
-  %}
   {{ options.inline ? '<span' : '<div' }} class="views-summary views-summary-unformatted">
   {% if row.separator -%}
     {{ row.separator }}
   {%- endif %}
-  <a href="{{ row.url }}"{{ row.attributes.addClass(row_classes) }}>{{ row.link }}</a>
+  {% if row.active %}
+    {% set row.attributes = row.attributes.addClass('active') %}
+  {% endif %}
+  <a href="{{ row.url }}"{{ row.attributes }}>{{ row.link }}</a>
   {% if options.count %}
     ({{ row.count }})
   {% endif %}