diff --git a/core/modules/block_content/config/schema/block_content.schema.yml b/core/modules/block_content/config/schema/block_content.schema.yml
index 2e7c338..756f020 100644
--- a/core/modules/block_content/config/schema/block_content.schema.yml
+++ b/core/modules/block_content/config/schema/block_content.schema.yml
@@ -16,3 +16,15 @@ block_content.type.*:
     description:
       type: text
       label: 'Description'
+
+migrate.source.d6_box:
+  type: migrate_source_sql
+  label: 'Drupal 6 box'
+  mapping:
+    constants:
+      type: mapping
+      label: 'Constants'
+      mapping:
+        type:
+          type: string
+          label: 'Type'
diff --git a/core/modules/migrate_drupal/migration_templates/d6_block_content_body_field.yml b/core/modules/block_content/migration_templates/d6_block_content_body_field.yml
similarity index 100%
rename from core/modules/migrate_drupal/migration_templates/d6_block_content_body_field.yml
rename to core/modules/block_content/migration_templates/d6_block_content_body_field.yml
diff --git a/core/modules/migrate_drupal/migration_templates/d6_block_content_type.yml b/core/modules/block_content/migration_templates/d6_block_content_type.yml
similarity index 100%
rename from core/modules/migrate_drupal/migration_templates/d6_block_content_type.yml
rename to core/modules/block_content/migration_templates/d6_block_content_type.yml
diff --git a/core/modules/migrate_drupal/migration_templates/d6_custom_block.yml b/core/modules/block_content/migration_templates/d6_custom_block.yml
similarity index 100%
rename from core/modules/migrate_drupal/migration_templates/d6_custom_block.yml
rename to core/modules/block_content/migration_templates/d6_custom_block.yml
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Box.php b/core/modules/block_content/src/Plugin/migrate/source/d6/Box.php
similarity index 87%
rename from core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Box.php
rename to core/modules/block_content/src/Plugin/migrate/source/d6/Box.php
index f8eec40..9596088 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Box.php
+++ b/core/modules/block_content/src/Plugin/migrate/source/d6/Box.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Plugin\migrate\source\d6\Box.
+ * Contains \Drupal\block_content\Plugin\migrate\source\d6\Box.
  */
 
-namespace Drupal\migrate_drupal\Plugin\migrate\source\d6;
+namespace Drupal\block_content\Plugin\migrate\source\d6;
 
 use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
 
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateBlockContentTest.php b/core/modules/block_content/src/Tests/Migrate/d6/MigrateBlockContentTest.php
similarity index 89%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateBlockContentTest.php
rename to core/modules/block_content/src/Tests/Migrate/d6/MigrateBlockContentTest.php
index 7b8dd9c..3a68161 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateBlockContentTest.php
+++ b/core/modules/block_content/src/Tests/Migrate/d6/MigrateBlockContentTest.php
@@ -2,17 +2,18 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateBlockContentTest.
+ * Contains \Drupal\block_content\Tests\Migrate\d6\MigrateBlockContentTest.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\block_content\Tests\Migrate\d6;
 
 use Drupal\block_content\Entity\BlockContent;
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
 
 /**
  * Upgrade custom blocks.
  *
- * @group migrate_drupal
+ * @group block_content
  */
 class MigrateBlockContentTest extends MigrateDrupal6TestBase {
 
diff --git a/core/modules/migrate_drupal/tests/src/Unit/source/d6/BoxTest.php b/core/modules/block_content/tests/src/Unit/Plugin/migrate/source/d6/BoxTest.php
similarity index 83%
rename from core/modules/migrate_drupal/tests/src/Unit/source/d6/BoxTest.php
rename to core/modules/block_content/tests/src/Unit/Plugin/migrate/source/d6/BoxTest.php
index fdd33ed..6c7ef21 100644
--- a/core/modules/migrate_drupal/tests/src/Unit/source/d6/BoxTest.php
+++ b/core/modules/block_content/tests/src/Unit/Plugin/migrate/source/d6/BoxTest.php
@@ -2,23 +2,23 @@
 
 /**
  * @file
- * Contains \Drupal\Tests\migrate_drupal\Unit\source\d6\BoxTest.
+ * Contains \Drupal\Tests\block_content\Unit\Plugin\migrate\source\d6\BoxTest.
  */
 
-namespace Drupal\Tests\migrate_drupal\Unit\source\d6;
+namespace Drupal\Tests\block_content\Unit\Plugin\migrate\source\d6;
 
 use Drupal\Tests\migrate\Unit\MigrateSqlSourceTestCase;
 
 /**
  * Tests D6 block boxes source plugin.
  *
- * @group migrate_drupal
+ * @group block_content
  */
 class BoxTest extends MigrateSqlSourceTestCase {
 
   // The plugin system is not working during unit testing so the source plugin
   // class needs to be manually specified.
-  const PLUGIN_CLASS = 'Drupal\migrate_drupal\Plugin\migrate\source\d6\Box';
+  const PLUGIN_CLASS = 'Drupal\block_content\Plugin\migrate\source\d6\Box';
 
   // The fake Migration configuration entity.
   protected $migrationConfiguration = array(
diff --git a/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml b/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
index 9fdf6d8..0e65909 100644
--- a/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
+++ b/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
@@ -75,18 +75,6 @@ migrate.source.d6_menu_link:
       type: migrate_entity_constant
       label: 'Constants'
 
-migrate.source.d6_box:
-  type: migrate_source_sql
-  label: 'Drupal 6 box'
-  mapping:
-    constants:
-      type: mapping
-      label: 'Constants'
-      mapping:
-        type:
-          type: string
-          label: 'Type'
-
 migrate.source.d6_taxonomy_vocabulary:
   type: migrate_source_sql
   label: 'Drupal 6 field instance form display'