diff --git a/core/modules/system/src/Controller/SystemController.php b/core/modules/system/src/Controller/SystemController.php
index a04724f..8e85527 100644
--- a/core/modules/system/src/Controller/SystemController.php
+++ b/core/modules/system/src/Controller/SystemController.php
@@ -241,7 +241,7 @@ public function themesPage() {
         if (isset($themes[$theme_key]) && file_exists($themes[$theme_key]->info['screenshot'])) {
           $theme->screenshot = [
             'uri' => $themes[$theme_key]->info['screenshot'],
-            'alt' => $this->t('Screenshot for @theme theme', ['@theme' => $theme->info['name']]),
+            'alt' => $this->t('<div>Screenshot for @theme theme</div>', ['@theme' => $theme->info['name']]),
             'title' => $this->t('Screenshot for @theme theme', ['@theme' => $theme->info['name']]),
             'attributes' => ['class' => ['screenshot']],
           ];