diff --git a/core/includes/entity.api.php b/core/includes/entity.api.php
index d385088..1bf3ef0 100644
--- a/core/includes/entity.api.php
+++ b/core/includes/entity.api.php
@@ -541,7 +541,7 @@ function hook_entity_field_access($operation, $field, $account) {
  * Alters the default access behaviour for a given field.
  *
  * Use this hook to override access grants from another module. Note that the
- * default access flag is masked under the umbrella of the system module.
+ * original default access flag is masked under the ':default' key.
  *
  * @param array $grants
  *   An array of grants gathered by hook_entity_field_access(). The array is
diff --git a/core/lib/Drupal/Core/Entity/Field/Type/Field.php b/core/lib/Drupal/Core/Entity/Field/Type/Field.php
index 39d4d2e..36c5f3a 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/Field.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/Field.php
@@ -296,9 +296,8 @@ public function access($operation = 'view', User $account = NULL) {
     // Get the default access restriction that lives within this field.
     $access = $this->defaultAccess($operation, $account);
     // Invoke hook and collect grants/denies for field access from other
-    // modules. Our default access flag is masked under the umbrella of the
-    // system module.
-    $grants = array('system' => $access);
+    // modules. Our default access flag is masked under the ':default' key.
+    $grants = array(':default' => $access);
     foreach (module_implements('entity_field_access') as $module) {
       $grants = array_merge($grants, array($module => module_invoke($module, 'entity_field_access', $operation, $this, $account)));
     }
diff --git a/core/modules/system/tests/modules/entity_test/entity_test.module b/core/modules/system/tests/modules/entity_test/entity_test.module
index 2594e78..6f94212 100644
--- a/core/modules/system/tests/modules/entity_test/entity_test.module
+++ b/core/modules/system/tests/modules/entity_test/entity_test.module
@@ -271,6 +271,6 @@ function entity_test_entity_field_access($operation, $field, $account) {
 function entity_test_entity_field_access_alter(array &$grants, array $context) {
   $field = $context['field'];
   if ($field->getName() == 'field_test_text' && $field->value == 'access alter value') {
-    $grants['system'] = FALSE;
+    $grants[':default'] = FALSE;
   }
 }