diff --git a/composer.json b/composer.json
index ce0f2a7..e40c309 100644
--- a/composer.json
+++ b/composer.json
@@ -17,10 +17,11 @@
         }
     ],
     "require": {
-        "silverstripe/framework": "^4.0"
+        "php": "^7.3 || ^8.0",
+        "silverstripe/framework": "^4.10"
     },
     "require-dev": {
-        "sminnee/phpunit": "^5.7",
+        "phpunit/phpunit": "^9.5",
         "silverstripe/versioned": "^1.0",
         "squizlabs/php_codesniffer": "^3.0"
     },
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index adb1fb0..45fd549 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,7 +1,9 @@
 <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/EditableSpamProtectionFieldTest.php b/tests/EditableSpamProtectionFieldTest.php
index 11010b0..0741db8 100644
--- a/tests/EditableSpamProtectionFieldTest.php
+++ b/tests/EditableSpamProtectionFieldTest.php
@@ -17,7 +17,7 @@ class EditableSpamProtectionFieldTest extends SapphireTest
 {
     protected $usesDatabase = true;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -115,7 +115,7 @@ class EditableSpamProtectionFieldTest extends SapphireTest
     {
         $field = new EditableSpamProtectionField;
 
-        $this->assertContains('/images/editablespamprotectionfield.png', $field->getIcon());
+        $this->assertStringContainsString('/images/editablespamprotectionfield.png', $field->getIcon());
     }
 
     protected function getFormMock()
diff --git a/tests/FormSpamProtectionExtensionTest.php b/tests/FormSpamProtectionExtensionTest.php
index 08e2c31..38d6071 100644
--- a/tests/FormSpamProtectionExtensionTest.php
+++ b/tests/FormSpamProtectionExtensionTest.php
@@ -25,7 +25,7 @@ class FormSpamProtectionExtensionTest extends SapphireTest
      */
     protected $form = null;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();