diff --git a/core/lib/Drupal/Core/Entity/EntityTypeManager.php b/core/lib/Drupal/Core/Entity/EntityTypeManager.php
index 9115da2..fdf71b1 100644
--- a/core/lib/Drupal/Core/Entity/EntityTypeManager.php
+++ b/core/lib/Drupal/Core/Entity/EntityTypeManager.php
@@ -75,7 +75,7 @@ class EntityTypeManager extends DefaultPluginManager implements EntityTypeManage
    *   The class resolver.
    */
   public function __construct(\Traversable $namespaces, ModuleHandlerInterface $module_handler, CacheBackendInterface $cache, TranslationInterface $string_translation, ClassResolverInterface $class_resolver) {
-    parent::__construct('Entity', $namespaces, $module_handler, 'Drupal\Core\Entity\EntityInterface');
+    parent::__construct('Entity', $namespaces, $module_handler, EntityInterface::class, EntityType::class);
 
     $this->setCacheBackend($cache, 'entity_type', ['entity_types']);
     $this->alterInfo('entity_type');
@@ -89,7 +89,8 @@ public function __construct(\Traversable $namespaces, ModuleHandlerInterface $mo
    */
   protected function getDiscovery() {
     if (!$this->discovery) {
-      $this->discovery = new AnnotatedClassDiscovery('Entity', $this->namespaces, EntityType::class);
+      // Opt out of derivative discovery set up by parent::getDiscovery().
+      $this->discovery = new AnnotatedClassDiscovery($this->subdir, $this->namespaces, $this->pluginDefinitionAnnotationName, $this->additionalAnnotationNamespaces);
     }
     return $this->discovery;
   }
diff --git a/core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php b/core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php
index 80c3df0..be636bf 100644
--- a/core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php
+++ b/core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php
@@ -23,6 +23,7 @@ protected function setUp() {
 
     // Fetch the definitions before installing the theme to prime the cache.
     \Drupal::service('breakpoint.manager')->getDefinitions();
+    // Installing a theme will reset the cached definitions and discovery.
     \Drupal::service('theme_handler')->install(['breakpoint_theme_test']);
   }