diff --git a/src/Entity/MediaBundle.php b/src/Entity/MediaBundle.php
index e7d3295..18151c6 100644
--- a/src/Entity/MediaBundle.php
+++ b/src/Entity/MediaBundle.php
@@ -256,9 +256,9 @@ class MediaBundle extends ConfigEntityBundleBase implements MediaBundleInterface
       // When creating new bundles, add also a source field, if configured to
       // do so.
       $media_type_manager = \Drupal::service('plugin.manager.media_entity.type');
+      $configuration = $this->getTypeConfiguration();
       /** @var \Drupal\media_entity\MediaTypeInterface $instance */
-      $instance = $media_type_manager->createInstance($this->getType()->getPluginId(), $this->getTypeConfiguration());
-      $configuration = $instance->getConfiguration();
+      $instance = $media_type_manager->createInstance($this->getType()->getPluginId(), $configuration);
 
       $source_field_info = $instance->getDefaultSourceField();
 
diff --git a/tests/modules/media_entity_test_type/src/Plugin/MediaEntity/Type/TestType.php b/tests/modules/media_entity_test_type/src/Plugin/MediaEntity/Type/TestType.php
index a2c5049..39e30d0 100644
--- a/tests/modules/media_entity_test_type/src/Plugin/MediaEntity/Type/TestType.php
+++ b/tests/modules/media_entity_test_type/src/Plugin/MediaEntity/Type/TestType.php
@@ -106,11 +106,13 @@ class TestType extends Generic {
       ]);
     }
     return [
-      'storage' => $storage,
-      'field_name' => static::MEDIA_ENTITY_TEST_TYPE_DEFAULT_FIELD_NAME,
-      'label' => $this->t('Test source field'),
-      'field_widget' => static::MEDIA_ENTITY_TEST_TYPE_DEFAULT_FIELD_WIDGET,
-      'field_formatter' => static::MEDIA_ENTITY_TEST_TYPE_DEFAULT_FIELD_FORMATTER,
+      'source_field' => [
+        'storage' => $storage,
+        'field_name' => static::MEDIA_ENTITY_TEST_TYPE_DEFAULT_FIELD_NAME,
+        'label' => $this->t('Test source field'),
+        'widget' => static::MEDIA_ENTITY_TEST_TYPE_DEFAULT_FIELD_WIDGET,
+        'formatter' => static::MEDIA_ENTITY_TEST_TYPE_DEFAULT_FIELD_FORMATTER,
+      ],
     ];
   }
 
diff --git a/tests/src/FunctionalJavascript/BundleCreationTest.php b/tests/src/FunctionalJavascript/BundleCreationTest.php
index 7483065..2a47df5 100644
--- a/tests/src/FunctionalJavascript/BundleCreationTest.php
+++ b/tests/src/FunctionalJavascript/BundleCreationTest.php
@@ -42,10 +42,12 @@ class BundleCreationTest extends MediaEntityJavascriptTestBase {
     $this->assertSession()->optionExists('type', 'test_type');
     $page->selectFieldOption('type', 'test_type');
     $this->waitForAjaxToFinish();
+$this->saveHtmlOutput();
 
     // Make sure the checkbox for creating the source field is there and save.
     $this->assertSession()->checkboxChecked('type_configuration[test_type][create_source_field]');
     $page->pressButton('Save media bundle');
+$this->saveHtmlOutput();
 
     // Check whether the source field was correctly created.
     // @TODO Finish me.