diff --git a/composer.json b/composer.json
index 9e003fe..300d547 100644
--- a/composer.json
+++ b/composer.json
@@ -20,12 +20,13 @@
         }
     ],
     "require": {
-        "silverstripe/framework": "^4.0",
+        "php": "^7.3 || ^8.0",
+        "silverstripe/framework": "^4.10",
         "silverstripe/versioned": "^1.0",
         "guzzlehttp/guzzle": "^6.3.3"
     },
     "require-dev": {
-        "sminnee/phpunit": "^5.7",
+        "phpunit/phpunit": "^9.5",
         "squizlabs/php_codesniffer": "^3.0"
     },
     "extra": [],
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 415aca1..5a7f2af 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,8 +1,10 @@
 <phpunit bootstrap="vendor/silverstripe/framework/tests/bootstrap.php" colors="true">
 
-	<testsuite name="Default">
-		<directory>tests</directory>
-	</testsuite>
+	<testsuites>
+		<testsuite name="Default">
+			<directory>tests</directory>
+		</testsuite>
+	</testsuites>
 
 	<filter>
 		<whitelist addUncoveredFilesFromWhitelist="true">
diff --git a/tests/Checks/DatabaseCheckTest.php b/tests/Checks/DatabaseCheckTest.php
index 0d18e08..aa4c411 100644
--- a/tests/Checks/DatabaseCheckTest.php
+++ b/tests/Checks/DatabaseCheckTest.php
@@ -10,8 +10,6 @@ use SilverStripe\Security\Member;
 /**
  * Class DatabaseCheckTest
  *
- * @mixin PHPUnit_Framework_TestCase
- *
  * @package environmentcheck
  */
 class DatabaseCheckTest extends SapphireTest
diff --git a/tests/Checks/ExternalURLCheckTest.php b/tests/Checks/ExternalURLCheckTest.php
index 8d0ec66..84db46d 100644
--- a/tests/Checks/ExternalURLCheckTest.php
+++ b/tests/Checks/ExternalURLCheckTest.php
@@ -9,8 +9,6 @@ use SilverStripe\EnvironmentCheck\EnvironmentCheck;
 /**
  * Class ExternalURLCheckTest
  *
- * @mixin PHPUnit_Framework_TestCase
- *
  * @package environmentcheck
  */
 class ExternalURLCheckTest extends SapphireTest
diff --git a/tests/Checks/FileWritableCheckTest.php b/tests/Checks/FileWritableCheckTest.php
index aba9e16..8683a34 100644
--- a/tests/Checks/FileWritableCheckTest.php
+++ b/tests/Checks/FileWritableCheckTest.php
@@ -9,8 +9,6 @@ use SilverStripe\Dev\SapphireTest;
 /**
  * Class FileWritableCheckTest
  *
- * @mixin PHPUnit_Framework_TestCase
- *
  * @package environmentcheck
  */
 class FileWritableCheckTest extends SapphireTest
diff --git a/tests/Checks/HasClassCheckTest.php b/tests/Checks/HasClassCheckTest.php
index a221c69..1617f5c 100644
--- a/tests/Checks/HasClassCheckTest.php
+++ b/tests/Checks/HasClassCheckTest.php
@@ -9,8 +9,6 @@ use SilverStripe\EnvironmentCheck\EnvironmentCheck;
 /**
  * Class HasClassCheckTest
  *
- * @mixin PHPUnit_Framework_TestCase
- *
  * @package environmentcheck
  */
 class HasClassCheckTest extends SapphireTest
diff --git a/tests/Checks/HasFunctionCheckTest.php b/tests/Checks/HasFunctionCheckTest.php
index 512934d..e82f528 100644
--- a/tests/Checks/HasFunctionCheckTest.php
+++ b/tests/Checks/HasFunctionCheckTest.php
@@ -9,8 +9,6 @@ use SilverStripe\Dev\SapphireTest;
 /**
  * Class HasFunctionCheckTest
  *
- * @mixin PHPUnit_Framework_TestCase
- *
  * @package environmentcheck
  */
 class HasFunctionCheckTest extends SapphireTest
diff --git a/tests/Checks/SessionCheckTest.php b/tests/Checks/SessionCheckTest.php
index a84bcef..47bbe43 100644
--- a/tests/Checks/SessionCheckTest.php
+++ b/tests/Checks/SessionCheckTest.php
@@ -25,7 +25,7 @@ class SessionCheckTest extends SapphireTest
      *
      * @return void
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->sessionCheck = new SessionCheck('/');
diff --git a/tests/Checks/URLCheckTest.php b/tests/Checks/URLCheckTest.php
index 8ff55b6..8a17c74 100644
--- a/tests/Checks/URLCheckTest.php
+++ b/tests/Checks/URLCheckTest.php
@@ -9,8 +9,6 @@ use SilverStripe\Dev\SapphireTest;
 /**
  * Class URLCheckTest
  *
- * @mixin PHPUnit_Framework_TestCase
- *
  * @package environmentcheck
  */
 class URLCheckTest extends SapphireTest
diff --git a/tests/Controllers/DevCheckControllerTest.php b/tests/Controllers/DevCheckControllerTest.php
index d39e8de..bf0798c 100644
--- a/tests/Controllers/DevCheckControllerTest.php
+++ b/tests/Controllers/DevCheckControllerTest.php
@@ -10,8 +10,6 @@ use SilverStripe\EnvironmentCheck\EnvironmentChecker;
 /**
  * Class DevCheckControllerTest
  *
- * @mixin PHPUnit_Framework_TestCase
- *
  * @package environmentcheck
  */
 class DevCheckControllerTest extends SapphireTest
diff --git a/tests/Controllers/DevHealthControllerTest.php b/tests/Controllers/DevHealthControllerTest.php
index dbaeb84..5dd2c98 100644
--- a/tests/Controllers/DevHealthControllerTest.php
+++ b/tests/Controllers/DevHealthControllerTest.php
@@ -10,8 +10,6 @@ use SilverStripe\EnvironmentCheck\EnvironmentChecker;
 /**
  * Class DevHealthControllerTest
  *
- * @mixin PHPUnit_Framework_TestCase
- *
  * @package environmentcheck
  */
 class DevHealthControllerTest extends SapphireTest
diff --git a/tests/EnvironmentCheckerTest.php b/tests/EnvironmentCheckerTest.php
index 77b21db..f8e2c02 100644
--- a/tests/EnvironmentCheckerTest.php
+++ b/tests/EnvironmentCheckerTest.php
@@ -20,7 +20,7 @@ class EnvironmentCheckerTest extends SapphireTest
 {
     protected $usesDatabase = true;
 
-    protected function tearDown()
+    protected function tearDown(): void
     {
         EnvironmentCheckSuite::reset();
         parent::tearDown();
@@ -61,8 +61,8 @@ class EnvironmentCheckerTest extends SapphireTest
         $logger->expects($this->once())
             ->method('log')
             ->withConsecutive(
-                $this->equalTo(LogLevel::WARNING),
-                $this->anything()
+                [$this->equalTo(LogLevel::WARNING)],
+                [$this->anything()]
             );
 
         Injector::inst()->registerService($logger, LoggerInterface::class);