diff --git a/composer.json b/composer.json
index af366a9..bf541c9 100644
--- a/composer.json
+++ b/composer.json
@@ -8,10 +8,12 @@
     ],
     "license": "BSD-3-Clause",
     "require": {
+        "php": "^7.3 || ^8.0",
+        "silverstripe/framework": "^4.10",
         "cwp/cwp": "^2"
     },
     "require-dev": {
-        "sminnee/phpunit": "^5.7",
+        "phpunit/phpunit": "^9.5",
         "squizlabs/php_codesniffer": "^3"
     },
     "extra": [],
diff --git a/tests/Extensions/PdfExportExtensionTest.php b/tests/Extensions/PdfExportExtensionTest.php
index 33a9a45..fa63398 100644
--- a/tests/Extensions/PdfExportExtensionTest.php
+++ b/tests/Extensions/PdfExportExtensionTest.php
@@ -18,7 +18,7 @@ class PdfExportExtensionTest extends SapphireTest
         ],
     ];
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -38,7 +38,7 @@ public function testPdfFilenameWithoutPublicDirectory($publicDir, $expected)
 
         /** @var BasePage|PdfExportExtension $page $page */
         $page = $this->objFromFixture(BasePage::class, 'test-page-one');
-        $this->assertContains($expected, $page->getPdfFilename());
+        $this->assertStringContainsString($expected, $page->getPdfFilename());
     }
 
     /**
@@ -55,13 +55,13 @@ public function pdfFilenameProvider()
     public function testPdfLink()
     {
         $page = $this->objFromFixture(BasePage::class, 'test-page-one');
-        $this->assertContains('test-page-one/downloadpdf', $page->PdfLink(), 'Link to download PDF');
+        $this->assertStringContainsString('test-page-one/downloadpdf', $page->PdfLink(), 'Link to download PDF');
     }
 
     public function testHomePagePdfLink()
     {
         $page = $this->objFromFixture(BasePage::class, 'home-page');
-        $this->assertContains('home/downloadpdf', $page->PdfLink(), 'Link to download PDF');
+        $this->assertStringContainsString('home/downloadpdf', $page->PdfLink(), 'Link to download PDF');
     }
 
     public function testPdfLinkDisabled()
diff --git a/tests/Tasks/CleanupGeneratedPdfDailyTaskTest.php b/tests/Tasks/CleanupGeneratedPdfDailyTaskTest.php
index f32b3bd..806d878 100644
--- a/tests/Tasks/CleanupGeneratedPdfDailyTaskTest.php
+++ b/tests/Tasks/CleanupGeneratedPdfDailyTaskTest.php
@@ -14,7 +14,7 @@ class CleanupGeneratedPdfDailyTaskTest extends SapphireTest
      */
     protected $task;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();