diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index b09bfa8..71bb768 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -262,6 +262,15 @@ function comment_field_config_delete(FieldConfigInterface $field) {
  */
 function comment_field_config_insert(FieldConfigInterface $field) {
   if ($field->getType() == 'comment') {
+    // Check that the target entity type uses an integer ID.
+    $entity_type_id = $field->getTargetEntityTypeId();
+    $entity_type = \Drupal::entityManager()->getDefinition($entity_type_id);
+    $entity_type_id_key = $entity_type->getKey('id');
+    $field_definitions = \Drupal::entityManager()->getBaseFieldDefinitions($entity_type->id());
+    $entity_type_id_definition = $field_definitions[$entity_type_id_key];
+    if ($entity_type_id_definition->getType() != 'integer') {
+      throw new \UnexpectedValueException(t('You cannot attach a comment field to an entity with a non-integer ID field.'));
+    }
     // Delete all fields and displays attached to the comment bundle.
     entity_invoke_bundle_hook('insert', 'comment', $field->getTargetEntityTypeId() . '__' . $field->getName());
   }
@@ -810,6 +819,15 @@ function comment_form_field_ui_field_overview_form_alter(&$form, $form_state) {
   if ($form['#entity_type'] == 'comment' && $request->attributes->has('commented_entity_type')) {
     $form['#title'] = \Drupal::service('comment.manager')->getFieldUIPageTitle($request->attributes->get('commented_entity_type'), $request->attributes->get('field_name'));
   }
+  $entity_type_id = $form['#entity_type'];
+  $entity_type = \Drupal::entityManager()->getDefinition($entity_type_id);
+  $entity_type_id_key = $entity_type->getKey('id');
+  $field_definitions = \Drupal::entityManager()->getBaseFieldDefinitions($entity_type->id());
+  $entity_type_id_definition = $field_definitions[$entity_type_id_key];
+  if ($entity_type_id_definition->getType() != 'integer') {
+    // You cannot use comment fields on entity types with non-integer IDs.
+    unset($form['fields']['_add_new_field']['type']['#options']['comment']);
+  }
 }
 
 /**
diff --git a/core/modules/comment/src/Tests/CommentNonNodeTest.php b/core/modules/comment/src/Tests/CommentNonNodeTest.php
index b5bb317..8f53832 100644
--- a/core/modules/comment/src/Tests/CommentNonNodeTest.php
+++ b/core/modules/comment/src/Tests/CommentNonNodeTest.php
@@ -382,4 +382,20 @@ function testCommentFunctionality() {
     $this->assertNoFieldByName('comment_body[0][value]', '', 'Comment field found.');
   }
 
+  /**
+   * Tests comment fields are not available for entity types with string ids.
+   */
+  public function testsStringIdEntities() {
+    // Create a bundle for entity_test.
+    entity_test_create_bundle('entity_test', 'Entity Test', 'entity_test_string_id');
+    $limited_user = $this->drupalCreateUser(array(
+      'administer entity_test_string_id fields',
+    ));
+    $this->drupalLogin($limited_user);
+    // Visit the Field UI overview.
+    $this->drupalGet('entity_test_string_id/structure/entity_test/fields');
+    // Ensure field isn't shown for string ids.
+    $this->assertNoOption('edit-fields-add-new-field-type', 'comment');
+  }
+
 }
diff --git a/core/modules/comment/src/Tests/CommentStringIdEntitiesTest.php b/core/modules/comment/src/Tests/CommentStringIdEntitiesTest.php
new file mode 100644
index 0000000..014b3b1
--- /dev/null
+++ b/core/modules/comment/src/Tests/CommentStringIdEntitiesTest.php
@@ -0,0 +1,57 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\comment\Tests\CommentStringIdEntitiesTest.
+ */
+
+namespace Drupal\comment\Tests;
+
+use Drupal\simpletest\KernelTestBase;
+
+/**
+ * Tests that comment fields cannot be added to entities with non-integer IDs.
+ */
+class CommentStringIdEntitiesTest extends KernelTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('comment', 'user', 'field', 'field_ui', 'entity_test');
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Comments on Entity Types with string IDs',
+      'description' => 'Test that comment fields cannot be added to entities with non-integer IDs',
+      'group' => 'Comment',
+    );
+  }
+
+  public function setUp() {
+    parent::setUp();
+    $this->installEntitySchema('comment');
+    $this->installSchema('comment', array('comment_entity_statistics'));
+  }
+
+  /**
+   * Tests that comment fields cannot be added entities with non-integer IDs.
+   */
+  public function testCommentFieldNonStringId() {
+    try {
+      $field = entity_create('field_config', array(
+        'name' => 'foo',
+        'entity_type' => 'entity_test_string_id',
+        'settings' => array(),
+        'type' => 'comment',
+      ));
+      $field->save();
+      $this->fail('Did not throw an exception as expected.');
+    }
+    catch (\UnexpectedValueException $e) {
+      $this->pass('Exception thrown when trying to create comment field on Entity Type with string ID.');
+    }
+  }
+
+}
diff --git a/core/modules/system/src/Tests/Entity/EntityApiTest.php b/core/modules/system/src/Tests/Entity/EntityApiTest.php
index caa7bb8..711a7a0 100644
--- a/core/modules/system/src/Tests/Entity/EntityApiTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityApiTest.php
@@ -29,6 +29,7 @@ public function setUp() {
     $this->installEntitySchema('entity_test_rev');
     $this->installEntitySchema('entity_test_mul');
     $this->installEntitySchema('entity_test_mulrev');
+    $this->installEntitySchema('entity_test_string_id');
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Entity/EntityFieldTest.php b/core/modules/system/src/Tests/Entity/EntityFieldTest.php
index 2091f0c..1cebff4 100644
--- a/core/modules/system/src/Tests/Entity/EntityFieldTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityFieldTest.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\system\Tests\Entity;
 
+use Drupal\entity_test\Entity\EntityTestStringId;
+
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Field\FieldDefinition;
 use Drupal\Core\Field\FieldDefinitionInterface;
@@ -48,6 +50,7 @@ public function setUp() {
     $this->installEntitySchema('entity_test_rev');
     $this->installEntitySchema('entity_test_mul');
     $this->installEntitySchema('entity_test_mulrev');
+    $this->installEntitySchema('entity_test_string_id');
 
     // Create the test field.
     entity_test_install();
@@ -322,7 +325,12 @@ protected function assertSave($entity_type) {
     $this->assertTrue((bool) $entity->id(), format_string('%entity_type: Entity loaded.', array('%entity_type' => $entity_type)));
 
     // Access the name field.
-    $this->assertEqual(1, $entity->id->value, format_string('%entity_type: ID value can be read.', array('%entity_type' => $entity_type)));
+    if ($entity_type == 'entity_test_string_id') {
+      $this->assertTrue(is_string($entity->id->value), format_string('%entity_type: ID value can be read.', array('%entity_type' => $entity_type)));
+    }
+    else {
+      $this->assertEqual(1, $entity->id->value, format_string('%entity_type: ID value can be read.', array('%entity_type' => $entity_type)));
+    }
     $this->assertTrue(is_string($entity->uuid->value), format_string('%entity_type: UUID value can be read.', array('%entity_type' => $entity_type)));
     $this->assertEqual(Language::LANGCODE_NOT_SPECIFIED, $entity->langcode->value, format_string('%entity_type: Language code can be read.', array('%entity_type' => $entity_type)));
     $this->assertEqual(\Drupal::languageManager()->getLanguage(Language::LANGCODE_NOT_SPECIFIED), $entity->langcode->language, format_string('%entity_type: Language object can be read.', array('%entity_type' => $entity_type)));
@@ -507,6 +515,24 @@ protected function assertDataStructureInterfaces($entity_type) {
       // Field format.
       NULL,
     );
+
+    // The entity id and the revision id of entity_test_string_id will have to
+    // be added in here as well.
+    if ($entity_type == 'entity_test_string_id') {
+      $target_strings = array(
+        NULL,
+        $entity->uuid->value,
+        Language::LANGCODE_NOT_SPECIFIED,
+        $this->entity_name,
+        // Bundle name.
+        $entity->bundle(),
+        NULL,
+        $this->entity_field_text,
+        // Field format.
+        NULL,
+      );
+    }
+
     $this->assertEqual($strings, $target_strings, format_string('%entity_type: All contained strings found.', array('%entity_type' => $entity_type)));
   }
 
diff --git a/core/modules/system/src/Tests/Entity/EntityLanguageTestBase.php b/core/modules/system/src/Tests/Entity/EntityLanguageTestBase.php
index c76fc97..9197154 100644
--- a/core/modules/system/src/Tests/Entity/EntityLanguageTestBase.php
+++ b/core/modules/system/src/Tests/Entity/EntityLanguageTestBase.php
@@ -53,6 +53,7 @@ function setUp() {
     $this->installEntitySchema('entity_test_rev');
     $this->installEntitySchema('entity_test_mul');
     $this->installEntitySchema('entity_test_mulrev');
+    $this->installEntitySchema('entity_test_string_id');
 
     $this->installConfig(array('language'));
 
diff --git a/core/modules/system/src/Tests/Entity/EntityRevisionsTest.php b/core/modules/system/src/Tests/Entity/EntityRevisionsTest.php
index b64ec89..15b10c3 100644
--- a/core/modules/system/src/Tests/Entity/EntityRevisionsTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityRevisionsTest.php
@@ -85,7 +85,7 @@ protected function assertRevisions($entity_type) {
       $revision_ids[] = $entity->revision_id->value;
 
       // Check that the fields and properties contain new content.
-      $this->assertTrue($entity->revision_id->value > $legacy_revision_id, format_string('%entity_type: Revision ID changed.', array('%entity_type' => $entity_type)));
+      $this->assertNotEqual($entity->revision_id->value, $legacy_revision_id, format_string('%entity_type: Revision ID changed.', array('%entity_type' => $entity_type)));
       $this->assertNotEqual($entity->name->value, $legacy_name, format_string('%entity_type: Name changed.', array('%entity_type' => $entity_type)));
       $this->assertNotEqual($entity->field_test_text->value, $legacy_text, format_string('%entity_type: Text changed.', array('%entity_type' => $entity_type)));
     }
diff --git a/core/modules/system/src/Tests/Entity/EntityUUIDTest.php b/core/modules/system/src/Tests/Entity/EntityUUIDTest.php
index a0ec726..39541d6 100644
--- a/core/modules/system/src/Tests/Entity/EntityUUIDTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityUUIDTest.php
@@ -26,6 +26,7 @@ public function setUp() {
     $this->installEntitySchema('entity_test_rev');
     $this->installEntitySchema('entity_test_mul');
     $this->installEntitySchema('entity_test_mulrev');
+    $this->installEntitySchema('entity_test_string_id');
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Entity/EntityValidationTest.php b/core/modules/system/src/Tests/Entity/EntityValidationTest.php
index dceab23..fa21882 100644
--- a/core/modules/system/src/Tests/Entity/EntityValidationTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityValidationTest.php
@@ -36,6 +36,7 @@ public function setUp() {
     $this->installEntitySchema('entity_test_rev');
     $this->installEntitySchema('entity_test_mul');
     $this->installEntitySchema('entity_test_mulrev');
+    $this->installEntitySchema('entity_test_string_id');
 
     // Create the test field.
     entity_test_install();
diff --git a/core/modules/system/tests/modules/entity_test/entity_test.install b/core/modules/system/tests/modules/entity_test/entity_test.install
index 015b067..fc656a9 100644
--- a/core/modules/system/tests/modules/entity_test/entity_test.install
+++ b/core/modules/system/tests/modules/entity_test/entity_test.install
@@ -14,6 +14,7 @@ function entity_test_install() {
     'entity_test_rev',
     'entity_test_mul',
     'entity_test_mulrev',
+    'entity_test_string_id',
   );
   foreach ($entity_types as $entity_type) {
     // Auto-create fields for testing.
diff --git a/core/modules/system/tests/modules/entity_test/entity_test.module b/core/modules/system/tests/modules/entity_test/entity_test.module
index 6c3a078..f91279c 100644
--- a/core/modules/system/tests/modules/entity_test/entity_test.module
+++ b/core/modules/system/tests/modules/entity_test/entity_test.module
@@ -55,6 +55,7 @@ function entity_test_entity_types($filter = NULL) {
     $types[] = 'entity_test_rev';
   }
   $types[] = 'entity_test_mulrev';
+  $types[] = 'entity_test_string_id';
   return array_combine($types, $types);
 }
 
diff --git a/core/modules/system/tests/modules/entity_test/entity_test.routing.yml b/core/modules/system/tests/modules/entity_test/entity_test.routing.yml
index 38b0c44..8e64681 100644
--- a/core/modules/system/tests/modules/entity_test/entity_test.routing.yml
+++ b/core/modules/system/tests/modules/entity_test/entity_test.routing.yml
@@ -34,6 +34,13 @@ entity_test.delete_entity_test_rev:
   requirements:
     _access: 'TRUE'
 
+entity_test.delete_entity_test_string_id:
+  path: '/entity_test/delete/entity_test_string_id/{entity_test_string_id}'
+  defaults:
+    _entity_form: entity_test_string_id.delete
+  requirements:
+    _access: 'TRUE'
+
 entity_test.render_options:
   path: '/entity_test_converter/{foo}'
   options:
diff --git a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestStringId.php b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestStringId.php
new file mode 100644
index 0000000..6a9585d
--- /dev/null
+++ b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestStringId.php
@@ -0,0 +1,84 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\entity_test\Entity\EntityTestStringId.
+ */
+
+namespace Drupal\entity_test\Entity;
+
+use Drupal\Core\Field\FieldDefinition;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Entity\EntityTypeInterface;
+
+
+/**
+ * Defines a test entity class with a string ID.
+ *
+ * @ContentEntityType(
+ *   id = "entity_test_string_id",
+ *   label = @Translation("Test entity with string_id"),
+ *   controllers = {
+ *     "access" = "Drupal\entity_test\EntityTestAccessController",
+ *     "form" = {
+ *       "default" = "Drupal\entity_test\EntityTestForm",
+ *       "delete" = "Drupal\entity_test\EntityTestDeleteForm"
+ *     },
+ *     "translation" = "Drupal\content_translation\ContentTranslationHandler"
+ *   },
+ *   base_table = "entity_test_string",
+ *   revision_table = "entity_test_string_revision",
+ *   fieldable = TRUE,
+ *   field_cache = TRUE,
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "revision" = "revision_id",
+ *     "uuid" = "uuid",
+ *     "bundle" = "type",
+ *     "label" = "name"
+ *   },
+ *   links = {
+ *     "canonical" = "entity_test.render",
+ *     "edit-form" = "entity_test.edit_entity_test_string_id",
+ *     "delete-form" = "entity_test.delete_entity_test_string_id",
+ *     "admin-form" = "entity_test.admin_entity_test_string_id"
+ *   }
+ * )
+ */
+class EntityTestStringId extends EntityTest {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function preSave(EntityStorageInterface $storage) {
+    parent::preSave($storage);
+    if ($this->isNew()) {
+      $this->set('id', substr(md5(rand()), 0, 10));
+    }
+    if ($this->isNewRevision()) {
+      $this->set('revision_id', substr(md5(rand()), 0, 10));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
+    $fields = parent::baseFieldDefinitions($entity_type);
+    $fields['id'] = FieldDefinition::create('string')
+      ->setLabel(t('ID'))
+      ->setDescription(t('The ID of the test entity.'))
+      ->setReadOnly(TRUE);
+
+    $fields['revision_id'] = FieldDefinition::create('string')
+      ->setLabel(t('Revision ID'))
+      ->setDescription(t('The version id of the test entity.'));
+
+    $fields['langcode']->setRevisionable(TRUE);
+    $fields['name']->setRevisionable(TRUE);
+    $fields['user_id']->setRevisionable(TRUE);
+
+    return $fields;
+  }
+
+}