diff --git a/tests/php/bootstrap.php b/tests/php/bootstrap.php
index 0447aa0..ccc4f3e 100644
--- a/tests/php/bootstrap.php
+++ b/tests/php/bootstrap.php
@@ -1,11 +1,19 @@
 <?php # -*- coding: utf-8 -*-
-$vendor = dirname(__DIR__, 2) . '/vendor/';
-if (!file_exists($vendor . 'autoload.php')) {
-    die("Please install via Composer before running tests.");
+/** @noinspection PhpIncludeInspection */
+declare(strict_types=1);
+
+putenv('TESTS_PATH='.__DIR__);
+putenv('LIBRARY_PATH='.dirname(__DIR__));
+
+$vendor = dirname(__DIR__, 2).'/vendor/';
+if (!realpath($vendor)) {
+    die('Please install via Composer before running tests.');
 }
 
-require_once $vendor . 'brain/monkey/inc/patchwork-loader.php';
-require_once $vendor . 'autoload.php';
-unset($vendor);
+if (!defined('PHPUNIT_COMPOSER_INSTALL')) {
+    define('PHPUNIT_COMPOSER_INSTALL', $vendor.'autoload.php');
+}
 
-putenv('TESTS_PATH=' . __DIR__);
+require_once $vendor.'brain/monkey/inc/patchwork-loader.php';
+require_once $vendor.'autoload.php';
+unset($vendor);
diff --git a/tests/php/unit/AssetsTest.php b/tests/php/unit/AssetsTest.php
index 83c7ed5..bb21826 100644
--- a/tests/php/unit/AssetsTest.php
+++ b/tests/php/unit/AssetsTest.php
@@ -1,4 +1,5 @@
 <?php # -*- coding: utf-8 -*-
+declare(strict_types=1);
 // phpcs:disable
 
 namespace MultisiteGlobalMedia\Tests\Unit;
diff --git a/tests/php/unit/AttachmentTest.php b/tests/php/unit/AttachmentTest.php
index d8ca3ac..c64c81b 100644
--- a/tests/php/unit/AttachmentTest.php
+++ b/tests/php/unit/AttachmentTest.php
@@ -1,4 +1,5 @@
 <?php # -*- coding: utf-8 -*-
+declare(strict_types=1);
 // phpcs:disable
 
 namespace MultisiteGlobalMedia\Tests\Unit;
@@ -8,8 +9,9 @@
 use MultisiteGlobalMedia\Attachment;
 use MultisiteGlobalMedia\Site;
 use MultisiteGlobalMedia\SiteSwitcher;
+use MultisiteGlobalMedia\Tests\TestCase;
 
-class AttachmentTest extends \MultisiteGlobalMedia\Tests\TestCase
+class AttachmentTest extends TestCase
 {
     public function testInstance()
     {
diff --git a/tests/php/unit/SiteTest.php b/tests/php/unit/SiteTest.php
index a329c44..dc5d7b8 100644
--- a/tests/php/unit/SiteTest.php
+++ b/tests/php/unit/SiteTest.php
@@ -1,4 +1,5 @@
 <?php # -*- coding: utf-8 -*-
+declare(strict_types=1);
 // phpcs:disable
 
 namespace MultisiteGlobalMedia\Tests\Unit;
@@ -6,6 +7,7 @@
 use Brain\Monkey\Filters;
 use MultisiteGlobalMedia\Site;
 use MultisiteGlobalMedia\Tests\TestCase;
+use PHPUnit\Framework\Exception;
 
 class SiteTest extends TestCase
 {
@@ -13,7 +15,11 @@ public function testInstance()
     {
         $testee = new Site();
 
-        self::assertInstanceOf(Site::class, $testee);
+        try {
+            self::assertInstanceOf(Site::class, $testee);
+        } catch (Exception $e) {
+            echo $e->getMessage();
+        }
     }
 
     public function testSiteIdFilterIsApplied()