diff --git a/core/modules/datetime/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
index ce0964d..cc030e7 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
@@ -17,6 +17,10 @@ class DateRangeWidgetBase extends DateTimeWidgetBase {
    */
   public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
     $element = parent::formElement($items, $delta, $element, $form, $form_state);
+    array_pop($element['#theme_wrappers']);
+    $element['#theme_wrappers'][] = 'fieldset';
+    array_pop($element['#attributes']['class']);
+
     $element['#element_validate'][] = [$this, 'validateStartEnd'];
     $element['value']['#title'] = $this->t('Start');