diff --git a/core/modules/simpletest/drupal_web_test_case.php b/core/modules/simpletest/drupal_web_test_case.php
index 7163739..a7f5d5b 100644
--- a/core/modules/simpletest/drupal_web_test_case.php
+++ b/core/modules/simpletest/drupal_web_test_case.php
@@ -742,11 +742,21 @@ class DrupalUnitTestCase extends DrupalTestCase {
       module_list(TRUE, FALSE, FALSE, $module_list);
     }
     $this->setup = TRUE;
+
+    // We're a unit test but the autoloader could still try and load from the
+    // database. Unregister it for the duration of the test.
+    spl_autoload_unregister('drupal_autoload_class');
+    spl_autoload_unregister('drupal_autoload_interface');
   }
 
   protected function tearDown() {
     global $conf;
 
+    // Test is done and we need to get the autoloader back before simpletest
+    // starts running again.
+    spl_autoload_register('drupal_autoload_interface');
+    spl_autoload_register('drupal_autoload_class');
+
     // Get back to the original connection.
     Database::removeConnection('default');
     Database::renameConnection('simpletest_original_default', 'default');
diff --git a/core/modules/simpletest/tests/registry.test b/core/modules/simpletest/tests/registry.test
index bcd8d4e..e241b2a 100644
--- a/core/modules/simpletest/tests/registry.test
+++ b/core/modules/simpletest/tests/registry.test
@@ -1,5 +1,24 @@
 <?php
 
+class RegistryUnitTest extends DrupalUnitTestCase {
+  public static function getInfo() {
+    return array(
+      'name' => 'Registry unit test de-registration',
+      'description' => 'Ensure the registry is not available for unit tests.',
+      'group' => 'System'
+    );
+  }
+
+  public function testPSR0Loading() {
+    // Instantiate a obscure Symfony class that shouldn't be loaded yet. We do
+    // not really have a system for PSR-0 test classes at the moment so even
+    // though its possible this could give us false positives, its fairly
+    // reasonable for the moment.
+    $loader = new Symfony\Component\HttpKernel\Bundle();
+    $this->assertTrue($loader, t('Non registry class autoloaded in a unit test.'));
+  }
+}
+
 class RegistryParseFileTestCase extends DrupalWebTestCase {
   public static function getInfo() {
     return array(