diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
index 77ffa8cfb1f..a53007a31b4 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
@@ -51,7 +51,7 @@ abstract class ConfigEntityBase extends Entity implements ConfigEntityInterface
    * since each configuration entity is unique.
    */
   final public function isNew() {
-    return !$this->id();
+    return $this->id() === NULL;
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Entity/Entity.php b/core/lib/Drupal/Core/Entity/Entity.php
index 8f462de7154..7f58bdf31a1 100644
--- a/core/lib/Drupal/Core/Entity/Entity.php
+++ b/core/lib/Drupal/Core/Entity/Entity.php
@@ -91,7 +91,7 @@ class Entity implements IteratorAggregate, EntityInterface {
    * Implements EntityInterface::isNew().
    */
   public function isNew() {
-    return !empty($this->enforceIsNew) || !$this->id();
+    return !empty($this->enforceIsNew) || $this->id() === NULL;
   }
 
   /**
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigEntityTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigEntityTest.php
index 532979c3110..45a16b92cfa 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigEntityTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigEntityTest.php
@@ -85,6 +85,19 @@ class ConfigEntityTest extends WebTestBase {
     $this->assertResponse(200);
     $this->assertNoText($label1);
     $this->assertText($label3);
+
+    // Create a configuration entity with '0' machine name.
+    $edit = array(
+      'id' => '0',
+      'label' => '0',
+    );
+    $this->drupalPost('admin/structure/config_test/add', $edit, 'Save');
+    $this->assertResponse(200);
+    $message_insert = format_string('%label configuration has been created.', array('%label' => $edit['id']));
+    $this->assertRaw($message_insert);
+
+    $this->drupalPost('admin/structure/config_test/manage/0/delete', array(), 'Delete');
+    $this->assertFalse(entity_load('config_test', '0'), 'Test entity deleted');
   }
 
 }