diff --git a/.phpcs.xml b/.phpcs.xml
index 7a910146d..25552ace3 100644
--- a/.phpcs.xml
+++ b/.phpcs.xml
@@ -2,6 +2,7 @@
 <ruleset>
 	<rule ref="./vendor/mediawiki/mediawiki-codesniffer/MediaWiki">
 		<exclude name="MediaWiki.Commenting.FunctionComment.MissingDocumentationPublic" />
+		<exclude name="PSR12.Properties.ConstantVisibility.NotFound" />
 	</rule>
 	<file>.</file>
 	<arg name="extensions" value="php,php5,inc"/>
diff --git a/composer.json b/composer.json
index f2060aad3..f10026ad8 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
 	"require-dev": {
 		"jakub-onderka/php-parallel-lint": "1.0.0",
-		"mediawiki/mediawiki-codesniffer": "26.0.0",
+		"mediawiki/mediawiki-codesniffer": "28.0.0",
 		"jakub-onderka/php-console-highlighter": "0.3.2",
 		"mediawiki/minus-x": "0.3.1",
 		"mediawiki/mediawiki-phan-config": "0.6.1"
diff --git a/tests/phpunit/CaptchaAuthenticationRequestTest.php b/tests/phpunit/CaptchaAuthenticationRequestTest.php
index aae874c16..67deed5db 100644
--- a/tests/phpunit/CaptchaAuthenticationRequestTest.php
+++ b/tests/phpunit/CaptchaAuthenticationRequestTest.php
@@ -6,7 +6,7 @@ use MediaWiki\Auth\AuthenticationRequestTestCase;
  * @covers CaptchaAuthenticationRequest
  */
 class CaptchaAuthenticationRequestTest extends AuthenticationRequestTestCase {
-	public function setUp() {
+	public function setUp() : void {
 		parent::setUp();
 		$this->setMwGlobals( [
 			'wgCaptchaClass' => SimpleCaptcha::class,
diff --git a/tests/phpunit/CaptchaPreAuthenticationProviderTest.php b/tests/phpunit/CaptchaPreAuthenticationProviderTest.php
index 39074c682..0cdab1a8e 100644
--- a/tests/phpunit/CaptchaPreAuthenticationProviderTest.php
+++ b/tests/phpunit/CaptchaPreAuthenticationProviderTest.php
@@ -9,7 +9,7 @@ use Wikimedia\TestingAccessWrapper;
  * @group Database
  */
 class CaptchaPreAuthenticationProviderTest extends MediaWikiTestCase {
-	public function setUp() {
+	public function setUp() : void {
 		parent::setUp();
 		$this->setMwGlobals( [
 			'wgCaptchaClass' => SimpleCaptcha::class,
@@ -28,7 +28,7 @@ class CaptchaPreAuthenticationProviderTest extends MediaWikiTestCase {
 		}
 	}
 
-	public function tearDown() {
+	public function tearDown() : void {
 		parent::tearDown();
 		// make sure $wgCaptcha resets between tests
 		TestingAccessWrapper::newFromClass( ConfirmEditHooks::class )->instanceCreated = false;
diff --git a/tests/phpunit/QuestyCaptchaTest.php b/tests/phpunit/QuestyCaptchaTest.php
index fc9679950..27310b723 100644
--- a/tests/phpunit/QuestyCaptchaTest.php
+++ b/tests/phpunit/QuestyCaptchaTest.php
@@ -5,7 +5,7 @@
  */
 class QuestyCaptchaTest extends MediaWikiTestCase {
 
-	public function setUp() {
+	public function setUp() : void {
 		parent::setUp();
 
 		$this->mergeMwGlobalArrayValue(
diff --git a/tests/phpunit/SimpleCaptcha/CaptchaTest.php b/tests/phpunit/SimpleCaptcha/CaptchaTest.php
index 2329212dc..1fbb94777 100644
--- a/tests/phpunit/SimpleCaptcha/CaptchaTest.php
+++ b/tests/phpunit/SimpleCaptcha/CaptchaTest.php
@@ -11,7 +11,7 @@ class CaptchaTest extends MediaWikiTestCase {
 	/** @var ScopedCallback[] */
 	private $hold = [];
 
-	public function tearDown() {
+	public function tearDown() : void {
 		// Destroy any ScopedCallbacks being held
 		$this->hold = [];
 		parent::tearDown();