core/modules/comment/comment.install | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/core/modules/comment/comment.install b/core/modules/comment/comment.install
index 47241c2..7618300 100644
--- a/core/modules/comment/comment.install
+++ b/core/modules/comment/comment.install
@@ -184,3 +184,13 @@ function comment_update_8301() {
   $entity_type->set('entity_keys', $keys);
   $definition_update_manager->updateEntityType($entity_type);
 }
+
+/**
+ * Make the entity_type field for comments required.
+ */
+function comment_update_8400() {
+  $definition_update_manager = \Drupal::entityDefinitionUpdateManager();
+  $field_definition = $definition_update_manager->getFieldStorageDefinition('entity_type', 'comment');
+  $field_definition->setRequired(TRUE);
+  $definition_update_manager->updateFieldStorageDefinition($field_definition);
+}