diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/TermFormController.php b/core/modules/taxonomy/lib/Drupal/taxonomy/TermFormController.php
index 744fd34..167befa 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/TermFormController.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/TermFormController.php
@@ -130,10 +130,10 @@ public function validate(array $form, array &$form_state) {
   }
 
   /**
-   * Overrides Drupal\Core\Entity\EntityFormController::submit().
+   * Overrides Drupal\Core\Entity\EntityFormController::buildEntity().
    */
-  public function submit(array $form, array &$form_state) {
-    $term = parent::submit($form, $form_state);
+  public function buildEntity(array $form, array &$form_state) {
+    $term = parent::buildEntity($form, $form_state);
 
     // Prevent leading and trailing spaces in term names.
     $term->name->value = trim($term->name->value);
@@ -143,6 +143,9 @@ public function submit(array $form, array &$form_state) {
     $term->description->value = $description['value'];
     $term->format->value = $description['format'];
 
+    // Assign parents with proper delta values starting from 0.
+    $term->parent = array_keys($form_state['values']['parent']);
+
     return $term;
   }
 
diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/TermStorageController.php b/core/modules/taxonomy/lib/Drupal/taxonomy/TermStorageController.php
index 26790c9..bea7976 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/TermStorageController.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/TermStorageController.php
@@ -79,11 +79,8 @@ protected function postDelete($entities) {
    */
   protected function postSave(EntityInterface $entity, $update) {
     // Only change the parents if a value is set, keep the existing values if
-    // not. They are keyed by term id if set through the UI, so take the first
-    // value.
-    $parents = $entity->parent->getValue();
-    $parent = reset($parents);
-    if (isset($parent['value'])) {
+    // not.
+    if (isset($entity->parent->value)) {
       db_delete('taxonomy_term_hierarchy')
         ->condition('tid', $entity->id())
         ->execute();