diff --git a/core/modules/config_translation/src/Controller/ConfigTranslationEntityListBuilder.php b/core/modules/config_translation/src/Controller/ConfigTranslationEntityListBuilder.php
index 2e0a241..dc68a29 100644
--- a/core/modules/config_translation/src/Controller/ConfigTranslationEntityListBuilder.php
+++ b/core/modules/config_translation/src/Controller/ConfigTranslationEntityListBuilder.php
@@ -67,7 +67,7 @@ public function render() {
    */
   public function buildRow(EntityInterface $entity) {
     $row['label']['data'] = $this->getLabel($entity);
-    $row['label']['class'] = 'table-filter-text-source';
+    $row['label']['class'][] = 'table-filter-text-source';
     return $row + parent::buildRow($entity);
   }