diff --git a/core/modules/field/field.api.php b/core/modules/field/field.api.php
index e8098ad..92e9eb6 100644
--- a/core/modules/field/field.api.php
+++ b/core/modules/field/field.api.php
@@ -411,12 +411,12 @@ function hook_field_info_max_weight($entity_type, $bundle, $context, $context_mo
  * To forbid the update from occurring, throw a
  * Drupal\field\FieldConfigUpdateForbiddenException.
  *
- * @param $field
+ * @param \Drupal\field\FieldConfigInterface $field
  *   The field as it will be post-update.
- * @param $prior_field
+ * @param \Drupal\field\FieldConfigInterface $prior_field
  *   The field as it is pre-update.
  */
-function hook_field_config_update_forbid($field, $prior_field) {
+function hook_field_config_update_forbid(\Drupal\field\FieldConfigInterface $field, \Drupal\field\FieldConfigInterface $prior_field) {
   // A 'list' field stores integer keys mapped to display values. If
   // the new field will have fewer values, and any data exists for the
   // abandoned keys, the field will have no way to display them. So,
diff --git a/core/modules/field/tests/modules/field_test/field_test.field.inc b/core/modules/field/tests/modules/field_test/field_test.field.inc
index 321fac8..79b57a3 100644
--- a/core/modules/field/tests/modules/field_test/field_test.field.inc
+++ b/core/modules/field/tests/modules/field_test/field_test.field.inc
@@ -9,6 +9,7 @@
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\FieldItemListInterface;
 use Drupal\Core\Session\AccountInterface;
+use Drupal\field\FieldConfigInterface;
 use Drupal\field\FieldConfigUpdateForbiddenException;
 
 /**
@@ -21,7 +22,7 @@ function field_test_field_widget_info_alter(&$info) {
 /**
  * Implements hook_field_config_update_forbid().
  */
-function field_test_field_config_update_forbid($field, $prior_field) {
+function field_test_field_config_update_forbid(FieldConfigInterface $field, FieldConfigInterface $prior_field) {
   if ($field->getType() == 'test_field' && $field->getSetting('unchangeable') != $prior_field->getSetting('unchangeable')) {
     throw new FieldConfigUpdateForbiddenException("field_test 'unchangeable' setting cannot be changed'");
   }
diff --git a/core/modules/options/options.module b/core/modules/options/options.module
index 0421b84..1d328f6 100644
--- a/core/modules/options/options.module
+++ b/core/modules/options/options.module
@@ -102,7 +102,7 @@ function options_allowed_values(FieldDefinitionInterface $field_definition, Enti
 /**
  * Implements hook_field_config_update_forbid().
  */
-function options_field_config_update_forbid($field, $prior_field) {
+function options_field_config_update_forbid(FieldConfigInterface $field, FieldConfigInterface $prior_field) {
   if ($field->module == 'options' && $field->hasData()) {
     // Forbid any update that removes allowed values with actual data.
     $allowed_values = $field->getSetting('allowed_values');