src/ResourceType/ResourceType.php               | 10 +++++-----
 tests/src/Functional/ActionTest.php             |  2 +-
 tests/src/Functional/FieldStorageConfigTest.php |  2 +-
 tests/src/Functional/WorkflowTest.php           |  2 +-
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/ResourceType/ResourceType.php b/src/ResourceType/ResourceType.php
index e45ac8e..8b3b98c 100644
--- a/src/ResourceType/ResourceType.php
+++ b/src/ResourceType/ResourceType.php
@@ -119,11 +119,11 @@ class ResourceType {
    */
   public function getPublicName($field_name) {
     // By default the entity field name is the public field name. Unless the
-    // public name is "id" or "type" — then they're prefixed with an underscore,
-    // because these are reserved by the JSON API spec.
+    // public name is "id" or "type" — then they're prefixed with the entity
+    // type ID because these are reserved by the JSON API spec.
     // @see http://jsonapi.org/format/#document-resource-object-fields
     if ($field_name === 'id' || $field_name === 'type') {
-      return "_$field_name";
+      return "{$this->entityTypeId}_$field_name";
     }
 
     return $field_name;
@@ -141,8 +141,8 @@ class ResourceType {
   public function getInternalName($field_name) {
     // By default the entity field name is the public field name. Unless: see
     // ::getPublicName().
-    if ($field_name === '_id' || $field_name === '_type') {
-      return substr($field_name, 1);
+    if ($field_name === "{$this->entityTypeId}_id" || $field_name === "{$this->entityTypeId}_type") {
+      return substr($field_name, strlen($this->entityTypeId));
     }
 
     return $field_name;
diff --git a/tests/src/Functional/ActionTest.php b/tests/src/Functional/ActionTest.php
index e7ef223..17c1e45 100644
--- a/tests/src/Functional/ActionTest.php
+++ b/tests/src/Functional/ActionTest.php
@@ -95,7 +95,7 @@ class ActionTest extends ResourceTestBase {
           'langcode' => 'en',
           'plugin' => 'user_add_role_action',
           'status' => TRUE,
-          '_type' => 'user',
+          'action_type' => 'user',
         ],
       ],
     ];
diff --git a/tests/src/Functional/FieldStorageConfigTest.php b/tests/src/Functional/FieldStorageConfigTest.php
index cfaaa8b..d600a00 100644
--- a/tests/src/Functional/FieldStorageConfigTest.php
+++ b/tests/src/Functional/FieldStorageConfigTest.php
@@ -95,7 +95,7 @@ class FieldStorageConfigTest extends ResourceTestBase {
           'settings' => [],
           'status' => TRUE,
           'translatable' => TRUE,
-          '_type' => 'boolean',
+          'field_storage_config_type' => 'boolean',
         ],
       ],
     ];
diff --git a/tests/src/Functional/WorkflowTest.php b/tests/src/Functional/WorkflowTest.php
index e5e6923..61cbc5b 100644
--- a/tests/src/Functional/WorkflowTest.php
+++ b/tests/src/Functional/WorkflowTest.php
@@ -94,7 +94,7 @@ class WorkflowTest extends ResourceTestBase {
           'label' => 'REST Worklow',
           'langcode' => 'en',
           'status' => TRUE,
-          '_type' => 'workflow_type_complex_test',
+          'workflow_type' => 'workflow_type_complex_test',
           'type_settings' => [
             'states' => [
               'draft' => [