diff --git a/core/modules/block/lib/Drupal/block/BlockBase.php b/core/modules/block/lib/Drupal/block/BlockBase.php
index fa603d2..b896b7d 100644
--- a/core/modules/block/lib/Drupal/block/BlockBase.php
+++ b/core/modules/block/lib/Drupal/block/BlockBase.php
@@ -168,7 +168,7 @@ public function getMachineNameSuggestion() {
     $transliteration_service = \Drupal::transliteration();
     $transliterated = $transliteration_service->transliterate($admin_label, Language::LANGCODE_DEFAULT, '_');
 
-    $replace_pattern = '[^a-z0-9_.]+';
+    $replace_pattern = '[^a-z0-9_]+';
 
     $transliterated = Unicode::strtolower($transliterated);
 
diff --git a/core/modules/block/lib/Drupal/block/BlockFormController.php b/core/modules/block/lib/Drupal/block/BlockFormController.php
index 92d3696..969d807 100644
--- a/core/modules/block/lib/Drupal/block/BlockFormController.php
+++ b/core/modules/block/lib/Drupal/block/BlockFormController.php
@@ -103,7 +103,6 @@ public function form(array $form, array &$form_state) {
       '#default_value' => !$entity->isNew() ? $entity->id() : $this->getUniqueMachineName($entity),
       '#machine_name' => array(
         'exists' => 'block_load',
-        'replace_pattern' => '[^a-z0-9_.]+',
         'source' => array('settings', 'label'),
       ),
       '#required' => TRUE,
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
index 58fc2d5..e7d0b42 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
@@ -37,7 +37,7 @@ function setUp() {
    */
   function testImport() {
     $name = 'system.site';
-    $dynamic_name = 'config_test.dynamic.new';
+    $dynamic_name = 'config_test.dynamic.new.test';
     $storage = $this->container->get('config.storage');
     $staging = $this->container->get('config.storage.staging');
 
@@ -52,7 +52,7 @@ function testImport() {
 
     // Create new config entity.
     $original_dynamic_data = array(
-      'id' => 'new',
+      'id' => 'new.test',
       'uuid' => '30df59bd-7b03-4cf7-bb35-d42fc49f0651',
       'label' => 'New',
       'weight' => 0,
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImporterTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImporterTest.php
index cb4aeaa..772c230 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImporterTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImporterTest.php
@@ -135,7 +135,7 @@ function testDeleted() {
    * Tests creation of configuration during import.
    */
   function testNew() {
-    $dynamic_name = 'config_test.dynamic.new';
+    $dynamic_name = 'config_test.dynamic.new.test';
     $storage = $this->container->get('config.storage');
     $staging = $this->container->get('config.storage.staging');
 
@@ -144,7 +144,7 @@ function testNew() {
 
     // Create new config entity.
     $original_dynamic_data = array(
-      'id' => 'new',
+      'id' => 'new.test',
       'uuid' => '30df59bd-7b03-4cf7-bb35-d42fc49f0651',
       'label' => 'New',
       'weight' => 0,
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigInstallWebTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigInstallWebTest.php
index 3bb7839..f8f21a1 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigInstallWebTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigInstallWebTest.php
@@ -34,7 +34,7 @@ function setUp() {
    */
   function testIntegrationModuleReinstallation() {
     $default_config = 'config_integration_test.settings';
-    $default_configuration_entity = 'config_test.dynamic.config_integration_test';
+    $default_configuration_entity = 'config_test.dynamic.config_integration.test';
 
     // Install the config_test module we're integrating with.
     \Drupal::moduleHandler()->install(array('config_test'));
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigOtherModuleTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigOtherModuleTest.php
index 90915fc..bfb6569 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigOtherModuleTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigOtherModuleTest.php
@@ -44,24 +44,24 @@ public function testInstallOtherModuleFirst() {
     // Check that the config entity doesn't exist before the config_test module
     // is enabled. We cannot use the entity system because the config_test
     // entity type does not exist.
-    $config = $this->container->get('config.factory')->get('config_test.dynamic.other_module');
+    $config = $this->container->get('config.factory')->get('config_test.dynamic.other.module');
     $this->assertTrue($config->isNew(), 'Default configuration for other modules is not installed if that module is not enabled.');
 
     // Install the module that provides the entity type. This installs the
     // default configuration.
     $this->moduleHandler->install(array('config_test'));
-    $this->assertTrue(entity_load('config_test', 'other_module', TRUE), 'Default configuration has been installed.');
+    $this->assertTrue(entity_load('config_test', 'other.module', TRUE), 'Default configuration has been installed.');
 
     // Uninstall the module that provides the entity type. This will remove the
     // default configuration.
     $this->moduleHandler->uninstall(array('config_test'));
-    $config = $this->container->get('config.factory')->get('config_test.dynamic.other_module');
+    $config = $this->container->get('config.factory')->get('config_test.dynamic.other.module');
     $this->assertTrue($config->isNew(), 'Default configuration for other modules is removed when the config entity provider is disabled.');
 
     // Install the module that provides the entity type again. This installs the
     // default configuration.
     $this->moduleHandler->install(array('config_test'));
-    $other_module_config_entity = entity_load('config_test', 'other_module', TRUE);
+    $other_module_config_entity = entity_load('config_test', 'other.module', TRUE);
     $this->assertTrue($other_module_config_entity, "Default configuration has been recreated.");
 
     // Update the default configuration to test that the changes are preserved
@@ -71,14 +71,14 @@ public function testInstallOtherModuleFirst() {
 
     // Uninstall the module that provides the default configuration.
     $this->moduleHandler->uninstall(array('config_other_module_config'));
-    $this->assertTrue(entity_load('config_test', 'other_module', TRUE), 'Default configuration for other modules is not removed when the module that provides it is uninstalled.');
+    $this->assertTrue(entity_load('config_test', 'other.module', TRUE), 'Default configuration for other modules is not removed when the module that provides it is uninstalled.');
 
     // Default configuration provided by config_test should still exist.
     $this->assertTrue(entity_load('config_test', 'dotted.default', TRUE), 'The configuration is not deleted.');
 
     // Re-enable module to test that default config is unchanged.
     $this->moduleHandler->install(array('config_other_module_config'));
-    $config_entity = entity_load('config_test', 'other_module', TRUE);
+    $config_entity = entity_load('config_test', 'other.module', TRUE);
     $this->assertEqual($config_entity->get('style'), "The piano ain't got no wrong notes.", 'Re-enabling the module does not install default config over the existing config entity.');
   }
 
@@ -87,10 +87,10 @@ public function testInstallOtherModuleFirst() {
    */
   public function testInstallConfigEnityModuleFirst() {
     $this->moduleHandler->install(array('config_test'));
-    $this->assertFalse(entity_load('config_test', 'other_module', TRUE), 'Default configuration provided by config_other_module_config does not exist.');
+    $this->assertFalse(entity_load('config_test', 'other.module', TRUE), 'Default configuration provided by config_other_module_config does not exist.');
 
     $this->moduleHandler->install(array('config_other_module_config'));
-    $this->assertTrue(entity_load('config_test', 'other_module', TRUE), 'Default configuration provided by config_other_module_config has been installed.');
+    $this->assertTrue(entity_load('config_test', 'other.module', TRUE), 'Default configuration provided by config_other_module_config has been installed.');
   }
 
 }
diff --git a/core/modules/config/tests/config_integration_test/config/config_test.dynamic.config_integration_test.yml b/core/modules/config/tests/config_integration_test/config/config_test.dynamic.config_integration.test.yml
similarity index 60%
rename from core/modules/config/tests/config_integration_test/config/config_test.dynamic.config_integration_test.yml
rename to core/modules/config/tests/config_integration_test/config/config_test.dynamic.config_integration.test.yml
index f87b942..7e9215d 100644
--- a/core/modules/config/tests/config_integration_test/config/config_test.dynamic.config_integration_test.yml
+++ b/core/modules/config/tests/config_integration_test/config/config_test.dynamic.config_integration.test.yml
@@ -1,2 +1,2 @@
-id: config_integration_test
+id: config_integration.test
 label: 'Default integration config label'
diff --git a/core/modules/config/tests/config_other_module_config/config/config_test.dynamic.other_module.yml b/core/modules/config/tests/config_other_module_config/config/config_test.dynamic.other.module.yml
similarity index 89%
rename from core/modules/config/tests/config_other_module_config/config/config_test.dynamic.other_module.yml
rename to core/modules/config/tests/config_other_module_config/config/config_test.dynamic.other.module.yml
index b144af6..8fdb1e9 100644
--- a/core/modules/config/tests/config_other_module_config/config/config_test.dynamic.other_module.yml
+++ b/core/modules/config/tests/config_other_module_config/config/config_test.dynamic.other.module.yml
@@ -1,4 +1,4 @@
-id: other_module
+id: other.module
 uuid: 486f9f5c-82ed-4add-a700-b0ee3af4d17d
 label: 'Other module'
 weight: '0'
diff --git a/core/modules/config/tests/config_test/config/schema/config_test.schema.yml b/core/modules/config/tests/config_test/config/schema/config_test.schema.yml
index 04329ab..9f02156 100644
--- a/core/modules/config/tests/config_test/config/schema/config_test.schema.yml
+++ b/core/modules/config/tests/config_test/config/schema/config_test.schema.yml
@@ -72,7 +72,7 @@ config_test.someschema.somemodule.*.*:
       type: text
       label: 'Description'
 
-config_test.dynamic.*:
+config_test.dynamic.*.*:
   type: mapping
   label: 'Config test entity'
   mapping:
diff --git a/core/modules/entity/lib/Drupal/entity/Form/EntityDisplayModeAddForm.php b/core/modules/entity/lib/Drupal/entity/Form/EntityDisplayModeAddForm.php
index 6eb2d2f..3d6c5f7 100644
--- a/core/modules/entity/lib/Drupal/entity/Form/EntityDisplayModeAddForm.php
+++ b/core/modules/entity/lib/Drupal/entity/Form/EntityDisplayModeAddForm.php
@@ -30,15 +30,6 @@ public function buildForm(array $form, array &$form_state, $entity_type = NULL)
   /**
    * {@inheritdoc}
    */
-  public function validate(array $form, array &$form_state) {
-    parent::validate($form, $form_state);
-
-    form_set_value($form['id'], $this->entityType . '.' . $form_state['values']['id'], $form_state);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
   protected function prepareEntity() {
     $definition = $this->entityManager->getDefinition($this->entityType);
     if (!$definition['fieldable'] || !isset($definition['controllers']['render'])) {
diff --git a/core/modules/entity/lib/Drupal/entity/Form/EntityDisplayModeFormBase.php b/core/modules/entity/lib/Drupal/entity/Form/EntityDisplayModeFormBase.php
index 93f595c..05254c6 100644
--- a/core/modules/entity/lib/Drupal/entity/Form/EntityDisplayModeFormBase.php
+++ b/core/modules/entity/lib/Drupal/entity/Form/EntityDisplayModeFormBase.php
@@ -80,15 +80,22 @@ public function form(array $form, array &$form_state) {
       '#default_value' => $this->entity->label(),
     );
 
+    if ($this->entity->isNew()) {
+      $machine_name = '';
+    }
+    else {
+      // The ID will be in the form "entity_type.user_configured_name". The
+      // entity type is prefixed during saving.
+      // @see \Drupal\entity\Form\EntityDisplayModeFormBase::save()
+      list(, $machine_name) = explode('.', $this->entity->id());
+    }
     $form['id'] = array(
       '#type' => 'machine_name',
       '#description' => t('A unique machine-readable name. Can only contain lowercase letters, numbers, and underscores.'),
       '#disabled' => !$this->entity->isNew(),
-      '#default_value' => $this->entity->id(),
-      '#field_prefix' => $this->entity->isNew() ? $this->entity->getTargetType() . '.' : '',
+      '#default_value' => $machine_name,
       '#machine_name' => array(
         'exists' => array($this, 'exists'),
-        'replace_pattern' => '[^a-z0-9_.]+',
       ),
     );
 
@@ -111,7 +118,7 @@ public function form(array $form, array &$form_state) {
   public function exists($entity_id, array $element, array $form_state) {
     return (bool) $this->queryFactory
       ->get($this->entity->entityType())
-      ->condition('id', $element['#field_prefix'] . $entity_id)
+      ->condition('id', $this->entity->getTargetType() . '.' . $entity_id)
       ->execute();
   }
 
@@ -119,6 +126,7 @@ public function exists($entity_id, array $element, array $form_state) {
    * {@inheritdoc}
    */
   public function save(array $form, array &$form_state) {
+    $this->entity->id = $this->entity->getTargetType() . '.' . $this->entity->id();
     drupal_set_message(t('Saved the %label @entity-type.', array('%label' => $this->entity->label(), '@entity-type' => strtolower($this->entityInfo['label']))));
     $this->entity->save();
     entity_info_cache_clear();