diff --git a/classes/LocaleManager.php b/classes/LocaleManager.php
index 70fdd6f..0b7032a 100644
--- a/classes/LocaleManager.php
+++ b/classes/LocaleManager.php
@@ -168,4 +168,14 @@ class LocaleManager
 
         return self::$instance;
     }
+
+    /**
+     * Destroy singleton instance.
+     *
+     * @return void
+     */
+    public static function destroyInstance()
+    {
+        self::$instance = null;
+    }
 }
diff --git a/tests/ControllerTest.php b/tests/ControllerTest.php
index fa6b02c..c703a7d 100644
--- a/tests/ControllerTest.php
+++ b/tests/ControllerTest.php
@@ -56,8 +56,8 @@ abstract class ControllerTest extends BaseTest
         $this->container = new Container();
         $this->request = Request::createFromEnvironment(Environment::mock());
         $this->response = new Response();
+        $this->container['locale'] = LocaleManager::getInstance();
         $this->container['view'] = ViewFactory::create($this->container, $this->request);
-        $this->container['locale'] = new LocaleManager();
 
         $frontController = new FrontController($this->container);
         $downloadController = new DownloadController($this->container);
diff --git a/tests/LocaleManagerTest.php b/tests/LocaleManagerTest.php
index 1bbc8a1..1ceb5d8 100644
--- a/tests/LocaleManagerTest.php
+++ b/tests/LocaleManagerTest.php
@@ -27,7 +27,7 @@ class LocaleManagerTest extends BaseTest
     protected function setUp()
     {
         $_SESSION[LocaleManager::class]['locale'] = 'foo_BAR';
-        $this->localeManager = new LocaleManager();
+        $this->localeManager = LocaleManager::getInstance();
     }
 
     /**
@@ -38,6 +38,7 @@ class LocaleManagerTest extends BaseTest
     protected function tearDown()
     {
         $this->localeManager->unsetLocale();
+        LocaleManager::destroyInstance();
     }
 
     /**
@@ -93,6 +94,7 @@ class LocaleManagerTest extends BaseTest
      */
     public function testEnv()
     {
+        putenv('LANG=foo_BAR');
         $this->localeManager->setLocale(new Locale('foo_BAR'));
         $this->assertEquals('foo_BAR', getenv('LANG'));
     }
diff --git a/tests/LocaleMiddlewareTest.php b/tests/LocaleMiddlewareTest.php
index 299e8ca..005e87e 100644
--- a/tests/LocaleMiddlewareTest.php
+++ b/tests/LocaleMiddlewareTest.php
@@ -39,7 +39,7 @@ class LocaleMiddlewareTest extends BaseTest
     protected function setUp()
     {
         $this->container = new Container();
-        $this->container['locale'] = new LocaleManager();
+        $this->container['locale'] = LocaleManager::getInstance();
         $this->middleware = new LocaleMiddleware($this->container);
     }
 
@@ -51,6 +51,7 @@ class LocaleMiddlewareTest extends BaseTest
     protected function tearDown()
     {
         $this->container['locale']->unsetLocale();
+        LocaleManager::destroyInstance();
     }
 
     /**
diff --git a/tests/ViewFactoryTest.php b/tests/ViewFactoryTest.php
index 163eeb1..45286c9 100644
--- a/tests/ViewFactoryTest.php
+++ b/tests/ViewFactoryTest.php
@@ -6,6 +6,7 @@
 
 namespace Alltube\Test;
 
+use Alltube\LocaleManager;
 use Alltube\ViewFactory;
 use Slim\Container;
 use Slim\Http\Environment;
@@ -24,7 +25,9 @@ class ViewFactoryTest extends BaseTest
      */
     public function testCreate()
     {
-        $view = ViewFactory::create(new Container());
+        $container = new Container();
+        $container['locale'] = LocaleManager::getInstance();
+        $view = ViewFactory::create($container);
         $this->assertInstanceOf(Smarty::class, $view);
     }
 
@@ -35,8 +38,10 @@ class ViewFactoryTest extends BaseTest
      */
     public function testCreateWithXForwardedProto()
     {
+        $container = new Container();
+        $container['locale'] = LocaleManager::getInstance();
         $request = Request::createFromEnvironment(Environment::mock());
-        $view = ViewFactory::create(new Container(), $request->withHeader('X-Forwarded-Proto', 'https'));
+        $view = ViewFactory::create($container, $request->withHeader('X-Forwarded-Proto', 'https'));
         $this->assertInstanceOf(Smarty::class, $view);
     }
 }