diff --git a/core/modules/entity/lib/Drupal/entity/Tests/EntityFormDisplayTest.php b/core/modules/entity/lib/Drupal/entity/Tests/EntityFormDisplayTest.php
index 25841ef..f30b69c 100644
--- a/core/modules/entity/lib/Drupal/entity/Tests/EntityFormDisplayTest.php
+++ b/core/modules/entity/lib/Drupal/entity/Tests/EntityFormDisplayTest.php
@@ -24,6 +24,11 @@ public static function getInfo() {
     );
   }
 
+  protected function setUp() {
+    parent::setUp();
+    $this->installConfig(array('field'));
+  }
+
   /**
    * Tests entity_get_form_display().
    */
diff --git a/core/modules/field_ui/field_ui.admin.inc b/core/modules/field_ui/field_ui.admin.inc
index 5acd486..fa9ebd1 100644
--- a/core/modules/field_ui/field_ui.admin.inc
+++ b/core/modules/field_ui/field_ui.admin.inc
@@ -5,6 +5,7 @@
  * Administrative interface for custom field type creation.
  */
 
+use Drupal\Component\Utility\NestedArray;
 use Drupal\field\Plugin\Core\Entity\FieldInstance;
 use Drupal\field_ui\FieldOverview;
 use Drupal\field_ui\DisplayOverview;
@@ -1010,8 +1011,8 @@ function field_ui_field_edit_form_submit($form, &$form_state) {
 
   // Handle widget settings.
   $options = $entity_form_display->getComponent($instance['field_name']);
-  $options['settings'] = $form_state['values']['instance']['widget']['settings'];
-  $entity_form_display->setComponent($instance['field_name'], $options);
+  $options['settings'] = NestedArray::mergeDeep($options['settings'], $form_state['values']['instance']['widget']['settings']);
+  $entity_form_display->setComponent($instance['field_name'], $options)->save();
   unset($form_state['values']['instance']['widget']);
 
   // Merge incoming values into the instance.