diff --git a/core/modules/comment/lib/Drupal/comment/Entity/Comment.php b/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
index 717eed5..5289a02 100644
--- a/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
+++ b/core/modules/comment/lib/Drupal/comment/Entity/Comment.php
@@ -289,10 +289,11 @@ public static function baseFieldDefinitions($entity_type) {
       ->setLabel(t('Entity type'))
       ->setDescription(t('The entity type to which this comment is attached.'));
 
-    $fields['field_id'] = FieldDefinition::create('entity_reference')
+    // @todo Convert to the entity_reference field in
+    // https://drupal.org/node/2149859.
+    $fields['field_id'] = FieldDefinition::create('string')
       ->setLabel(t('Field ID'))
-      ->setDescription(t('The comment field id.'))
-      ->setSetting('target_type', 'field_entity');
+      ->setDescription(t('The comment field id.'));
 
     $fields['field_name'] = FieldDefinition::create('string')
       ->setLabel(t('Comment field name'))
diff --git a/core/modules/comment/lib/Drupal/comment/Tests/CommentValidationTest.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentValidationTest.php
index 90cac5d..220c4f8 100644
--- a/core/modules/comment/lib/Drupal/comment/Tests/CommentValidationTest.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentValidationTest.php
@@ -44,6 +44,20 @@ public function setUp() {
    * Tests the comment validation constraints.
    */
   public function testValidation() {
+    // Add comment field to content.
+    $this->entityManager->getStorageController('field_entity')->create(array(
+      'entity_type' => 'node',
+      'name' => 'comment',
+      'type' => 'comment',
+    ))->save();
+    // Add comment field instance to page content.
+    $this->entityManager->getStorageController('field_instance')->create(array(
+      'field_name' => 'comment',
+      'entity_type' => 'node',
+      'bundle' => 'page',
+      'label' => 'Comment settings',
+    ))->save();
+
     $node = $this->entityManager->getStorageController('node')->create(array(
       'type' => 'page',
       'title' => 'test',
@@ -52,9 +66,8 @@ public function testValidation() {
 
     $comment = $this->entityManager->getStorageController('comment')->create(array(
       'entity_id' => $node->id(),
-      // Just use some non-existing dummy field ID here, we are not testing
-      // that.
-      'field_id' => 'test',
+      'entity_type' => 'node',
+      'field_name' => 'comment',
     ));
     $violations = $comment->validate();
     $this->assertEqual(count($violations), 0, 'No violations when validating a default comment.');