diff --git a/core/modules/block/lib/Drupal/block/BlockBase.php b/core/modules/block/lib/Drupal/block/BlockBase.php
index f1217c0..d27d41a 100644
--- a/core/modules/block/lib/Drupal/block/BlockBase.php
+++ b/core/modules/block/lib/Drupal/block/BlockBase.php
@@ -11,6 +11,7 @@
 use Drupal\block\BlockInterface;
 use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Language\Language;
+use Drupal\user\Plugin\Core\Entity\User;
 
 /**
  * Defines a base block implementation that most blocks plugins will extend.
@@ -75,7 +76,7 @@ public function setConfigurationValue($key, $value) {
   /**
    * {@inheritdoc}
    */
-  public function access() {
+  public function access(User $user = null) {
     // By default, the block is visible unless user-configured rules indicate
     // that it should be hidden.
     return TRUE;
diff --git a/core/modules/block/lib/Drupal/block/BlockPluginInterface.php b/core/modules/block/lib/Drupal/block/BlockPluginInterface.php
index 5f353a4..9df84c8 100644
--- a/core/modules/block/lib/Drupal/block/BlockPluginInterface.php
+++ b/core/modules/block/lib/Drupal/block/BlockPluginInterface.php
@@ -10,6 +10,7 @@
 use Drupal\Component\Plugin\PluginInspectionInterface;
 use Drupal\Component\Plugin\ConfigurablePluginInterface;
 use Drupal\Core\Plugin\PluginFormInterface;
+use Drupal\user\Plugin\Core\Entity\User;
 
 /**
  * Defines the required interface for all block plugins.
@@ -38,13 +39,15 @@ public function settings();
    *
    * This method allows base implementations to add general access restrictions
    * that should apply to all extending block plugins.
-   *
+   * 
+   * @param \Drupal\user\Plugin\Core\Entity\User $user
+   *   (optional) User entity to check access for.
    * @return bool
    *   TRUE if the block should be shown, or FALSE otherwise.
    *
    * @see \Drupal\block\BlockAccessController
    */
-  public function access();
+  public function access(User $user = NULL);
 
   /**
    * Builds and returns the renderable array for this block plugin.