diff --git a/modules/update/tests/update_test.module b/modules/update/tests/update_test.module
index 34608363af7f31f1eccac208e9557542994593bd..9b8de5b45f25ddc9a85d305e694a2362407ab8a6 100644
--- a/modules/update/tests/update_test.module
+++ b/modules/update/tests/update_test.module
@@ -99,3 +99,16 @@ function update_test_mock_page($project_name) {
   $path = drupal_get_path('module', 'update_test');
   readfile("$path/$project_name.$availability_scenario.xml");
 }
+
+/**
+ * Implement hook_archiver_info().
+ */
+function update_test_archiver_info() {
+  return array(
+    'update_test_archiver' => array(
+      // This is bogus, we only care about the extensions for now.
+      'class' => 'ArchiverUpdateTest',
+      'extensions' => array('update-test-extension'),
+    ),
+  );
+}
diff --git a/modules/update/update.test b/modules/update/update.test
index 2b6d84dccca4106f927b57a50fba5a97cd0dc247..fcf4ea91c92089618dc341c6aa88bdef9bfc02df 100644
--- a/modules/update/update.test
+++ b/modules/update/update.test
@@ -564,7 +564,7 @@ class UpdateTestUploadCase extends UpdateTestHelper {
   }
 
   public function setUp() {
-    parent::setUp('update');
+    parent::setUp('update', 'update_test');
     variable_set('allow_authorize_operations', TRUE);
     $admin_user = $this->drupalCreateUser(array('administer software updates', 'administer site configuration'));
     $this->drupalLogin($admin_user);
@@ -593,5 +593,15 @@ class UpdateTestUploadCase extends UpdateTestHelper {
     $this->drupalPost('admin/modules/install', $edit, t('Install'));
     $this->assertText(t('@module_name is already installed.', array('@module_name' => 'AAA Update test')), 'Existing module was extracted and not reinstalled.');
   }
-}
 
+  /**
+   * Ensure that archiver extensions are properly merged in the UI.
+   */
+  function testFileNameExtensionMerging() {
+    $this->drupalGet('admin/modules/install');    
+    // Make sure the bogus extension supported by update_test.module is there.
+    $this->assertPattern('/archive extensions are supported:.*update-test-extension/', t("Found 'update-test-extension' extension"));
+    // Make sure it didn't clobber the first option from core.
+    $this->assertPattern('/archive extensions are supported:.*zip/', t("Found 'zip' extension"));
+  }
+}