diff --git a/README.md b/README.md
index 0cac7ebf..2906917c 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ Please read the [CONTRIBUTING.md](CONTRIBUTING.md) and [DEVELOPMENT.md](DEVELOPM
 The Engelsystem may be installed manually or by using the provided [docker setup](#docker).
 
 ### Requirements
- * PHP >= 7.2
+ * PHP >= 7.3
    * Required modules:
      * dom
      * json
diff --git a/composer.json b/composer.json
index 2921fe7d..94294231 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,7 @@
         "phpcbf": "phpcbf -p"
     },
     "require": {
-        "php": ">=7.2.0",
+        "php": ">=7.3.0",
         "ext-json": "*",
         "ext-libxml": "*",
         "ext-mbstring": "*",
@@ -45,9 +45,9 @@
         "vlucas/phpdotenv": "^3.3"
     },
     "require-dev": {
-        "dms/phpunit-arraysubset-asserts": "^0.1.0",
+        "dms/phpunit-arraysubset-asserts": "^0.2.0",
         "filp/whoops": "^2.3",
-        "phpunit/phpunit": "^8.1",
+        "phpunit/phpunit": "^9.1",
         "squizlabs/php_codesniffer": "^3.5",
         "symfony/var-dumper": "^4.3"
     },
diff --git a/phpunit.xml b/phpunit.xml
index 98e64795..a5ae4cec 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,6 +1,6 @@
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         bootstrap="./tests/autoload.php"
-         xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/6.3/phpunit.xsd"
+         xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/9.1/phpunit.xsd"
+         bootstrap="./includes/autoload.php"
          colors="true"
 >
     <testsuites>
diff --git a/tests/Unit/Mail/EngelsystemMailerTest.php b/tests/Unit/Mail/EngelsystemMailerTest.php
index cdbdf435..b35fb0b2 100644
--- a/tests/Unit/Mail/EngelsystemMailerTest.php
+++ b/tests/Unit/Mail/EngelsystemMailerTest.php
@@ -37,7 +37,7 @@ class EngelsystemMailerTest extends TestCase
         $this->setExpects($view, 'render', ['test/template.tpl', ['dev' => true]], 'Rendered Stuff!');
 
         $return = $mailer->sendView('foo@bar.baz', 'Lorem dolor', 'test/template.tpl', ['dev' => true]);
-        $this->equalTo(1, $return);
+        $this->assertEquals(1, $return);
     }
 
     /**
@@ -91,7 +91,7 @@ class EngelsystemMailerTest extends TestCase
             ['dev' => true],
             'de_DE'
         );
-        $this->equalTo(1, $return);
+        $this->assertEquals(1, $return);
     }
 
     /**
@@ -120,6 +120,6 @@ class EngelsystemMailerTest extends TestCase
         $this->assertEquals('Mail test', $mailer->getSubjectPrefix());
 
         $return = $mailer->send('to@xam.pel', 'Foo Bar', 'Lorem Ipsum!');
-        $this->equalTo(1, $return);
+        $this->assertEquals(1, $return);
     }
 }
diff --git a/tests/Unit/Mail/MailerTest.php b/tests/Unit/Mail/MailerTest.php
index bfecdd07..a0edc11a 100644
--- a/tests/Unit/Mail/MailerTest.php
+++ b/tests/Unit/Mail/MailerTest.php
@@ -72,6 +72,6 @@ class MailerTest extends TestCase
         $mailer->setFromName('Lorem Ipsum');
 
         $return = $mailer->send('to@xam.pel', 'Foo Bar', 'Lorem Ipsum!');
-        $this->equalTo(1, $return);
+        $this->assertEquals(1, $return);
     }
 }
diff --git a/tests/Unit/Mail/Transport/LogTransportTest.php b/tests/Unit/Mail/Transport/LogTransportTest.php
index 6e67f648..a6d64931 100644
--- a/tests/Unit/Mail/Transport/LogTransportTest.php
+++ b/tests/Unit/Mail/Transport/LogTransportTest.php
@@ -52,6 +52,6 @@ class LogTransportTest extends TestCase
             ->willReturn(['foo@bar.batz' => null, 'lor@em.ips' => 'Lorem Ipsum']);
 
         $return = $transport->send($message);
-        $this->equalTo(2, $return);
+        $this->assertEquals(2, $return);
     }
 }
diff --git a/tests/Unit/Renderer/HtmlEngineTest.php b/tests/Unit/Renderer/HtmlEngineTest.php
index f76e7528..cb8578d3 100644
--- a/tests/Unit/Renderer/HtmlEngineTest.php
+++ b/tests/Unit/Renderer/HtmlEngineTest.php
@@ -65,7 +65,7 @@ class HtmlEngineTest extends TestCase
     protected function tearDown(): void
     {
         foreach ($this->tmpFileNames as $fileName) {
-            unlink($fileName);
+            file_exists($fileName) && unlink($fileName);
         }
     }
 }
diff --git a/tests/autoload.php b/tests/autoload.php
deleted file mode 100644
index ba79bad9..00000000
--- a/tests/autoload.php
+++ /dev/null
@@ -1,3 +0,0 @@
-<?php
-
-require_once __DIR__ . '/../includes/autoload.php';