diff --git a/core/modules/jsonapi/tests/src/Kernel/Normalizer/FieldItemNormalizerTest.php b/core/modules/jsonapi/tests/src/Kernel/Normalizer/FieldItemNormalizerTest.php
index 2275d08080..86f5c597ac 100644
--- a/core/modules/jsonapi/tests/src/Kernel/Normalizer/FieldItemNormalizerTest.php
+++ b/core/modules/jsonapi/tests/src/Kernel/Normalizer/FieldItemNormalizerTest.php
@@ -29,7 +29,6 @@ class FieldItemNormalizerTest extends JsonapiKernelTestBase {
     'entity_test',
     'serialization',
     'jsonapi',
-    'jsonapi_test_field_type',
   ];
 
   /**
diff --git a/core/modules/jsonapi/tests/modules/jsonapi_test_field_type/src/Plugin/Field/FieldType/NoMainPropertyNameTestFieldItem.php b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/NoMainPropertyNameTestFieldItem.php
similarity index 90%
rename from core/modules/jsonapi/tests/modules/jsonapi_test_field_type/src/Plugin/Field/FieldType/NoMainPropertyNameTestFieldItem.php
rename to core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/NoMainPropertyNameTestFieldItem.php
index 41614c5149..19c27a0a01 100644
--- a/core/modules/jsonapi/tests/modules/jsonapi_test_field_type/src/Plugin/Field/FieldType/NoMainPropertyNameTestFieldItem.php
+++ b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/NoMainPropertyNameTestFieldItem.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\jsonapi_test_field_type\Plugin\Field\FieldType;
+namespace Drupal\entity_test\Plugin\Field\FieldType;
 
 use Drupal\Core\Field\Plugin\Field\FieldType\StringItem;
 
diff --git a/core/modules/jsonapi/tests/modules/jsonapi_test_field_type/src/Plugin/Field/FieldType/SingleInternalPropertyTestFieldItem.php b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/SingleInternalPropertyTestFieldItem.php
similarity index 95%
rename from core/modules/jsonapi/tests/modules/jsonapi_test_field_type/src/Plugin/Field/FieldType/SingleInternalPropertyTestFieldItem.php
rename to core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/SingleInternalPropertyTestFieldItem.php
index a6d3d37377..30add62df1 100644
--- a/core/modules/jsonapi/tests/modules/jsonapi_test_field_type/src/Plugin/Field/FieldType/SingleInternalPropertyTestFieldItem.php
+++ b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/SingleInternalPropertyTestFieldItem.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\jsonapi_test_field_type\Plugin\Field\FieldType;
+namespace Drupal\entity_test\Plugin\Field\FieldType;
 
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\Core\Field\Plugin\Field\FieldType\StringItem;