diff --git a/includes/AbuseFilterServices.php b/includes/AbuseFilterServices.php
index d258695f4..34f565903 100644
--- a/includes/AbuseFilterServices.php
+++ b/includes/AbuseFilterServices.php
@@ -24,7 +24,7 @@ use Psr\Container\ContainerInterface;
 
 class AbuseFilterServices {
 
-	public static function getHookRunner( ContainerInterface $services = null ): AbuseFilterHookRunner {
+	public static function getHookRunner( ?ContainerInterface $services = null ): AbuseFilterHookRunner {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( AbuseFilterHookRunner::SERVICE_NAME );
 	}
 
@@ -32,7 +32,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return KeywordsManager
 	 */
-	public static function getKeywordsManager( ContainerInterface $services = null ): KeywordsManager {
+	public static function getKeywordsManager( ?ContainerInterface $services = null ): KeywordsManager {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( KeywordsManager::SERVICE_NAME );
 	}
 
@@ -40,7 +40,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return FilterProfiler
 	 */
-	public static function getFilterProfiler( ContainerInterface $services = null ): FilterProfiler {
+	public static function getFilterProfiler( ?ContainerInterface $services = null ): FilterProfiler {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( FilterProfiler::SERVICE_NAME );
 	}
 
@@ -48,7 +48,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return AbuseFilterPermissionManager
 	 */
-	public static function getPermissionManager( ContainerInterface $services = null ): AbuseFilterPermissionManager {
+	public static function getPermissionManager( ?ContainerInterface $services = null ): AbuseFilterPermissionManager {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( AbuseFilterPermissionManager::SERVICE_NAME );
 	}
 
@@ -56,7 +56,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return ChangeTagger
 	 */
-	public static function getChangeTagger( ContainerInterface $services = null ): ChangeTagger {
+	public static function getChangeTagger( ?ContainerInterface $services = null ): ChangeTagger {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( ChangeTagger::SERVICE_NAME );
 	}
 
@@ -64,7 +64,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return ChangeTagsManager
 	 */
-	public static function getChangeTagsManager( ContainerInterface $services = null ): ChangeTagsManager {
+	public static function getChangeTagsManager( ?ContainerInterface $services = null ): ChangeTagsManager {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( ChangeTagsManager::SERVICE_NAME );
 	}
 
@@ -72,7 +72,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return ChangeTagValidator
 	 */
-	public static function getChangeTagValidator( ContainerInterface $services = null ): ChangeTagValidator {
+	public static function getChangeTagValidator( ?ContainerInterface $services = null ): ChangeTagValidator {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( ChangeTagValidator::SERVICE_NAME );
 	}
 
@@ -80,7 +80,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return BlockAutopromoteStore
 	 */
-	public static function getBlockAutopromoteStore( ContainerInterface $services = null ): BlockAutopromoteStore {
+	public static function getBlockAutopromoteStore( ?ContainerInterface $services = null ): BlockAutopromoteStore {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( BlockAutopromoteStore::SERVICE_NAME );
 	}
 
@@ -88,7 +88,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return FilterUser
 	 */
-	public static function getFilterUser( ContainerInterface $services = null ): FilterUser {
+	public static function getFilterUser( ?ContainerInterface $services = null ): FilterUser {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( FilterUser::SERVICE_NAME );
 	}
 
@@ -96,7 +96,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return CentralDBManager
 	 */
-	public static function getCentralDBManager( ContainerInterface $services = null ): CentralDBManager {
+	public static function getCentralDBManager( ?ContainerInterface $services = null ): CentralDBManager {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( CentralDBManager::SERVICE_NAME );
 	}
 
@@ -104,7 +104,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return RuleCheckerFactory
 	 */
-	public static function getRuleCheckerFactory( ContainerInterface $services = null ): RuleCheckerFactory {
+	public static function getRuleCheckerFactory( ?ContainerInterface $services = null ): RuleCheckerFactory {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( RuleCheckerFactory::SERVICE_NAME );
 	}
 
@@ -112,7 +112,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return FilterLookup
 	 */
-	public static function getFilterLookup( ContainerInterface $services = null ): FilterLookup {
+	public static function getFilterLookup( ?ContainerInterface $services = null ): FilterLookup {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( FilterLookup::SERVICE_NAME );
 	}
 
@@ -120,7 +120,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return EmergencyCache
 	 */
-	public static function getEmergencyCache( ContainerInterface $services = null ): EmergencyCache {
+	public static function getEmergencyCache( ?ContainerInterface $services = null ): EmergencyCache {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( EmergencyCache::SERVICE_NAME );
 	}
 
@@ -128,7 +128,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return EmergencyWatcher
 	 */
-	public static function getEmergencyWatcher( ContainerInterface $services = null ): EmergencyWatcher {
+	public static function getEmergencyWatcher( ?ContainerInterface $services = null ): EmergencyWatcher {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( EmergencyWatcher::SERVICE_NAME );
 	}
 
@@ -136,7 +136,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return EchoNotifier
 	 */
-	public static function getEchoNotifier( ContainerInterface $services = null ): EchoNotifier {
+	public static function getEchoNotifier( ?ContainerInterface $services = null ): EchoNotifier {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( EchoNotifier::SERVICE_NAME );
 	}
 
@@ -144,7 +144,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return FilterValidator
 	 */
-	public static function getFilterValidator( ContainerInterface $services = null ): FilterValidator {
+	public static function getFilterValidator( ?ContainerInterface $services = null ): FilterValidator {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( FilterValidator::SERVICE_NAME );
 	}
 
@@ -152,7 +152,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return FilterCompare
 	 */
-	public static function getFilterCompare( ContainerInterface $services = null ): FilterCompare {
+	public static function getFilterCompare( ?ContainerInterface $services = null ): FilterCompare {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( FilterCompare::SERVICE_NAME );
 	}
 
@@ -160,7 +160,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return FilterImporter
 	 */
-	public static function getFilterImporter( ContainerInterface $services = null ): FilterImporter {
+	public static function getFilterImporter( ?ContainerInterface $services = null ): FilterImporter {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( FilterImporter::SERVICE_NAME );
 	}
 
@@ -168,7 +168,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return FilterStore
 	 */
-	public static function getFilterStore( ContainerInterface $services = null ): FilterStore {
+	public static function getFilterStore( ?ContainerInterface $services = null ): FilterStore {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( FilterStore::SERVICE_NAME );
 	}
 
@@ -176,7 +176,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return ConsequencesFactory
 	 */
-	public static function getConsequencesFactory( ContainerInterface $services = null ): ConsequencesFactory {
+	public static function getConsequencesFactory( ?ContainerInterface $services = null ): ConsequencesFactory {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( ConsequencesFactory::SERVICE_NAME );
 	}
 
@@ -184,7 +184,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return EditBoxBuilderFactory
 	 */
-	public static function getEditBoxBuilderFactory( ContainerInterface $services = null ): EditBoxBuilderFactory {
+	public static function getEditBoxBuilderFactory( ?ContainerInterface $services = null ): EditBoxBuilderFactory {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( EditBoxBuilderFactory::SERVICE_NAME );
 	}
 
@@ -192,7 +192,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return ConsequencesLookup
 	 */
-	public static function getConsequencesLookup( ContainerInterface $services = null ): ConsequencesLookup {
+	public static function getConsequencesLookup( ?ContainerInterface $services = null ): ConsequencesLookup {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( ConsequencesLookup::SERVICE_NAME );
 	}
 
@@ -200,7 +200,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return ConsequencesRegistry
 	 */
-	public static function getConsequencesRegistry( ContainerInterface $services = null ): ConsequencesRegistry {
+	public static function getConsequencesRegistry( ?ContainerInterface $services = null ): ConsequencesRegistry {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( ConsequencesRegistry::SERVICE_NAME );
 	}
 
@@ -208,7 +208,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return AbuseLoggerFactory
 	 */
-	public static function getAbuseLoggerFactory( ContainerInterface $services = null ): AbuseLoggerFactory {
+	public static function getAbuseLoggerFactory( ?ContainerInterface $services = null ): AbuseLoggerFactory {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( AbuseLoggerFactory::SERVICE_NAME );
 	}
 
@@ -216,7 +216,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return UpdateHitCountWatcher
 	 */
-	public static function getUpdateHitCountWatcher( ContainerInterface $services = null ): UpdateHitCountWatcher {
+	public static function getUpdateHitCountWatcher( ?ContainerInterface $services = null ): UpdateHitCountWatcher {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( UpdateHitCountWatcher::SERVICE_NAME );
 	}
 
@@ -224,7 +224,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return VariablesBlobStore
 	 */
-	public static function getVariablesBlobStore( ContainerInterface $services = null ): VariablesBlobStore {
+	public static function getVariablesBlobStore( ?ContainerInterface $services = null ): VariablesBlobStore {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( VariablesBlobStore::SERVICE_NAME );
 	}
 
@@ -233,7 +233,7 @@ class AbuseFilterServices {
 	 * @return ConsequencesExecutorFactory
 	 */
 	public static function getConsequencesExecutorFactory(
-		ContainerInterface $services = null
+		?ContainerInterface $services = null
 	): ConsequencesExecutorFactory {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( ConsequencesExecutorFactory::SERVICE_NAME );
 	}
@@ -242,7 +242,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return FilterRunnerFactory
 	 */
-	public static function getFilterRunnerFactory( ContainerInterface $services = null ): FilterRunnerFactory {
+	public static function getFilterRunnerFactory( ?ContainerInterface $services = null ): FilterRunnerFactory {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( FilterRunnerFactory::SERVICE_NAME );
 	}
 
@@ -250,7 +250,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return SpecsFormatter
 	 */
-	public static function getSpecsFormatter( ContainerInterface $services = null ): SpecsFormatter {
+	public static function getSpecsFormatter( ?ContainerInterface $services = null ): SpecsFormatter {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( SpecsFormatter::SERVICE_NAME );
 	}
 
@@ -258,7 +258,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return VariablesFormatter
 	 */
-	public static function getVariablesFormatter( ContainerInterface $services = null ): VariablesFormatter {
+	public static function getVariablesFormatter( ?ContainerInterface $services = null ): VariablesFormatter {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( VariablesFormatter::SERVICE_NAME );
 	}
 
@@ -266,7 +266,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return LazyVariableComputer
 	 */
-	public static function getLazyVariableComputer( ContainerInterface $services = null ): LazyVariableComputer {
+	public static function getLazyVariableComputer( ?ContainerInterface $services = null ): LazyVariableComputer {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( LazyVariableComputer::SERVICE_NAME );
 	}
 
@@ -274,7 +274,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return TextExtractor
 	 */
-	public static function getTextExtractor( ContainerInterface $services = null ): TextExtractor {
+	public static function getTextExtractor( ?ContainerInterface $services = null ): TextExtractor {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( TextExtractor::SERVICE_NAME );
 	}
 
@@ -282,7 +282,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return VariablesManager
 	 */
-	public static function getVariablesManager( ContainerInterface $services = null ): VariablesManager {
+	public static function getVariablesManager( ?ContainerInterface $services = null ): VariablesManager {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( VariablesManager::SERVICE_NAME );
 	}
 
@@ -291,7 +291,7 @@ class AbuseFilterServices {
 	 * @return VariableGeneratorFactory
 	 */
 	public static function getVariableGeneratorFactory(
-		ContainerInterface $services = null
+		?ContainerInterface $services = null
 	): VariableGeneratorFactory {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( VariableGeneratorFactory::SERVICE_NAME );
 	}
@@ -300,7 +300,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return EditRevUpdater
 	 */
-	public static function getEditRevUpdater( ContainerInterface $services = null ): EditRevUpdater {
+	public static function getEditRevUpdater( ?ContainerInterface $services = null ): EditRevUpdater {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( EditRevUpdater::SERVICE_NAME );
 	}
 
@@ -308,7 +308,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return BlockedDomainStorage
 	 */
-	public static function getBlockedDomainStorage( ContainerInterface $services = null ): BlockedDomainStorage {
+	public static function getBlockedDomainStorage( ?ContainerInterface $services = null ): BlockedDomainStorage {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( BlockedDomainStorage::SERVICE_NAME );
 	}
 
@@ -316,7 +316,7 @@ class AbuseFilterServices {
 	 * @param ContainerInterface|null $services
 	 * @return BlockedDomainFilter
 	 */
-	public static function getBlockedDomainFilter( ContainerInterface $services = null ): BlockedDomainFilter {
+	public static function getBlockedDomainFilter( ?ContainerInterface $services = null ): BlockedDomainFilter {
 		return ( $services ?? MediaWikiServices::getInstance() )->get( BlockedDomainFilter::SERVICE_NAME );
 	}
 }
diff --git a/includes/Hooks/Handlers/AutoPromoteGroupsHandler.php b/includes/Hooks/Handlers/AutoPromoteGroupsHandler.php
index 77e8d67e4..6f7f5acf5 100644
--- a/includes/Hooks/Handlers/AutoPromoteGroupsHandler.php
+++ b/includes/Hooks/Handlers/AutoPromoteGroupsHandler.php
@@ -28,7 +28,7 @@ class AutoPromoteGroupsHandler implements GetAutoPromoteGroupsHook {
 	public function __construct(
 		ConsequencesRegistry $consequencesRegistry,
 		BlockAutopromoteStore $blockAutopromoteStore,
-		BagOStuff $cache = null
+		?BagOStuff $cache = null
 	) {
 		$this->cache = $cache ?? new HashBagOStuff();
 		$this->consequencesRegistry = $consequencesRegistry;
diff --git a/includes/Parser/AFPSyntaxTree.php b/includes/Parser/AFPSyntaxTree.php
index 352df97e1..6551eb2f1 100644
--- a/includes/Parser/AFPSyntaxTree.php
+++ b/includes/Parser/AFPSyntaxTree.php
@@ -16,7 +16,7 @@ class AFPSyntaxTree {
 	/**
 	 * @param AFPTreeNode|null $root
 	 */
-	public function __construct( AFPTreeNode $root = null ) {
+	public function __construct( ?AFPTreeNode $root = null ) {
 		$this->rootNode = $root;
 	}
 
diff --git a/includes/Parser/FilterEvaluator.php b/includes/Parser/FilterEvaluator.php
index f0ad5da72..1e5e5acbd 100644
--- a/includes/Parser/FilterEvaluator.php
+++ b/includes/Parser/FilterEvaluator.php
@@ -216,7 +216,7 @@ class FilterEvaluator {
 		IBufferingStatsdDataFactory $statsdDataFactory,
 		Equivset $equivset,
 		int $conditionsLimit,
-		VariableHolder $vars = null
+		?VariableHolder $vars = null
 	) {
 		$this->contLang = $contLang;
 		$this->cache = $cache;
diff --git a/includes/Parser/RuleCheckerFactory.php b/includes/Parser/RuleCheckerFactory.php
index 47f0be340..7b258c87d 100644
--- a/includes/Parser/RuleCheckerFactory.php
+++ b/includes/Parser/RuleCheckerFactory.php
@@ -72,7 +72,7 @@ class RuleCheckerFactory {
 	 * @param VariableHolder|null $vars
 	 * @return FilterEvaluator
 	 */
-	public function newRuleChecker( VariableHolder $vars = null ): FilterEvaluator {
+	public function newRuleChecker( ?VariableHolder $vars = null ): FilterEvaluator {
 		return new FilterEvaluator(
 			$this->contLang,
 			$this->cache,
diff --git a/includes/VariableGenerator/RCVariableGenerator.php b/includes/VariableGenerator/RCVariableGenerator.php
index da75c6746..2e7381111 100644
--- a/includes/VariableGenerator/RCVariableGenerator.php
+++ b/includes/VariableGenerator/RCVariableGenerator.php
@@ -53,7 +53,7 @@ class RCVariableGenerator extends VariableGenerator {
 		WikiPageFactory $wikiPageFactory,
 		RecentChange $rc,
 		User $contextUser,
-		VariableHolder $vars = null
+		?VariableHolder $vars = null
 	) {
 		parent::__construct( $hookRunner, $userFactory, $vars );
 
diff --git a/includes/VariableGenerator/RunVariableGenerator.php b/includes/VariableGenerator/RunVariableGenerator.php
index f732eb01a..1b0f029c8 100644
--- a/includes/VariableGenerator/RunVariableGenerator.php
+++ b/includes/VariableGenerator/RunVariableGenerator.php
@@ -60,7 +60,7 @@ class RunVariableGenerator extends VariableGenerator {
 		WikiPageFactory $wikiPageFactory,
 		User $user,
 		Title $title,
-		VariableHolder $vars = null
+		?VariableHolder $vars = null
 	) {
 		parent::__construct( $hookRunner, $userFactory, $vars );
 		$this->textExtractor = $textExtractor;
@@ -152,7 +152,7 @@ class RunVariableGenerator extends VariableGenerator {
 		Content $newcontent,
 		string $text,
 		string $oldtext,
-		Content $oldcontent = null
+		?Content $oldcontent = null
 	): VariableHolder {
 		$this->addUserVars( $this->user )
 			->addTitleVars( $this->title, 'page' );
diff --git a/includes/VariableGenerator/VariableGenerator.php b/includes/VariableGenerator/VariableGenerator.php
index 656146a9d..74a0e2752 100644
--- a/includes/VariableGenerator/VariableGenerator.php
+++ b/includes/VariableGenerator/VariableGenerator.php
@@ -34,7 +34,7 @@ class VariableGenerator {
 	public function __construct(
 		AbuseFilterHookRunner $hookRunner,
 		UserFactory $userFactory,
-		VariableHolder $vars = null
+		?VariableHolder $vars = null
 	) {
 		$this->hookRunner = $hookRunner;
 		$this->userFactory = $userFactory;
@@ -56,7 +56,7 @@ class VariableGenerator {
 	 *   this is the entry. Null if it's for the current action being filtered.
 	 * @return $this For chaining
 	 */
-	public function addGenericVars( RecentChange $rc = null ): self {
+	public function addGenericVars( ?RecentChange $rc = null ): self {
 		$timestamp = $rc
 			? MWTimestamp::convert( TS_UNIX, $rc->getAttribute( 'rc_timestamp' ) )
 			: wfTimestamp( TS_UNIX );
@@ -76,7 +76,7 @@ class VariableGenerator {
 	 *   this is the entry. Null if it's for the current action being filtered.
 	 * @return $this For chaining
 	 */
-	public function addUserVars( UserIdentity $userIdentity, RecentChange $rc = null ): self {
+	public function addUserVars( UserIdentity $userIdentity, ?RecentChange $rc = null ): self {
 		$asOf = $rc ? $rc->getAttribute( 'rc_timestamp' ) : wfTimestampNow();
 		$user = $this->userFactory->newFromUserIdentity( $userIdentity );
 
@@ -148,7 +148,7 @@ class VariableGenerator {
 	public function addTitleVars(
 		Title $title,
 		string $prefix,
-		RecentChange $rc = null
+		?RecentChange $rc = null
 	): self {
 		if ( $rc && $rc->getAttribute( 'rc_type' ) == RC_NEW ) {
 			$this->vars->setVar( $prefix . '_id', 0 );
@@ -239,7 +239,7 @@ class VariableGenerator {
 		WikiPage $page,
 		UserIdentity $userIdentity,
 		bool $forFilter = true,
-		PreparedUpdate $update = null
+		?PreparedUpdate $update = null
 	): self {
 		$this->addDerivedEditVars();
 
diff --git a/includes/VariableGenerator/VariableGeneratorFactory.php b/includes/VariableGenerator/VariableGeneratorFactory.php
index 09f5c2708..4e72f9cbe 100644
--- a/includes/VariableGenerator/VariableGeneratorFactory.php
+++ b/includes/VariableGenerator/VariableGeneratorFactory.php
@@ -57,7 +57,7 @@ class VariableGeneratorFactory {
 	 * @param VariableHolder|null $holder
 	 * @return VariableGenerator
 	 */
-	public function newGenerator( VariableHolder $holder = null ): VariableGenerator {
+	public function newGenerator( ?VariableHolder $holder = null ): VariableGenerator {
 		return new VariableGenerator( $this->hookRunner, $this->userFactory, $holder );
 	}
 
@@ -67,7 +67,7 @@ class VariableGeneratorFactory {
 	 * @param VariableHolder|null $holder
 	 * @return RunVariableGenerator
 	 */
-	public function newRunGenerator( User $user, Title $title, VariableHolder $holder = null ): RunVariableGenerator {
+	public function newRunGenerator( User $user, Title $title, ?VariableHolder $holder = null ): RunVariableGenerator {
 		return new RunVariableGenerator(
 			$this->hookRunner,
 			$this->userFactory,
@@ -89,7 +89,7 @@ class VariableGeneratorFactory {
 	public function newRCGenerator(
 		RecentChange $rc,
 		User $contextUser,
-		VariableHolder $holder = null
+		?VariableHolder $holder = null
 	): RCVariableGenerator {
 		return new RCVariableGenerator(
 			$this->hookRunner,
diff --git a/tests/phpunit/AbuseFilterCreateAccountTestTrait.php b/tests/phpunit/AbuseFilterCreateAccountTestTrait.php
index 276df5256..bf88daf62 100644
--- a/tests/phpunit/AbuseFilterCreateAccountTestTrait.php
+++ b/tests/phpunit/AbuseFilterCreateAccountTestTrait.php
@@ -22,7 +22,7 @@ trait AbuseFilterCreateAccountTestTrait {
 	protected function createAccount(
 		string $accountName,
 		bool $autocreate = false,
-		User $creator = null
+		?User $creator = null
 	): StatusValue {
 		$userFactory = MediaWikiServices::getInstance()->getUserFactory();
 		$user = $userFactory->newFromName( $accountName );
diff --git a/tests/phpunit/RCVariableGeneratorTest.php b/tests/phpunit/RCVariableGeneratorTest.php
index 12b99e994..e65a4991a 100644
--- a/tests/phpunit/RCVariableGeneratorTest.php
+++ b/tests/phpunit/RCVariableGeneratorTest.php
@@ -41,7 +41,7 @@ class RCVariableGeneratorTest extends MediaWikiIntegrationTestCase {
 	 * @covers \MediaWiki\Extension\AbuseFilter\VariableGenerator\RCVariableGenerator
 	 * @dataProvider provideRCRowTypes
 	 */
-	public function testGetVarsFromRCRow( string $type, string $action, UserIdentity $userIdentity = null ) {
+	public function testGetVarsFromRCRow( string $type, string $action, ?UserIdentity $userIdentity = null ) {
 		if ( $userIdentity && !$userIdentity->isRegistered() ) {
 			// If we are testing anonymous user, make sure we disable temp accounts.
 			$this->disableAutoCreateTempUser();
diff --git a/tests/phpunit/integration/ActionVariablesIntegrationTest.php b/tests/phpunit/integration/ActionVariablesIntegrationTest.php
index 4f0750d47..038304990 100644
--- a/tests/phpunit/integration/ActionVariablesIntegrationTest.php
+++ b/tests/phpunit/integration/ActionVariablesIntegrationTest.php
@@ -93,7 +93,7 @@ class ActionVariablesIntegrationTest extends ApiTestCase {
 		$this->setService( ConsequencesLookup::SERVICE_NAME, $consequencesLookup );
 	}
 
-	private function setAbuseLoggerFactoryWithEavesdrop( VariableHolder &$varHolder = null ): void {
+	private function setAbuseLoggerFactoryWithEavesdrop( ?VariableHolder &$varHolder = null ): void {
 		$factory = $this->createMock( AbuseLoggerFactory::class );
 		$factory->method( 'newLogger' )
 			->willReturnCallback( function ( $title, $user, $vars ) use ( &$varHolder ) {
@@ -298,7 +298,7 @@ class ActionVariablesIntegrationTest extends ApiTestCase {
 	 * @covers \MediaWiki\Extension\AbuseFilter\Variables\LazyVariableComputer
 	 */
 	public function testEditVariables(
-		array $expected, array $params, Content $oldContent = null
+		array $expected, array $params, ?Content $oldContent = null
 	) {
 		$time = time();
 		MWTimestamp::setFakeTime( $time );
@@ -386,7 +386,7 @@ class ActionVariablesIntegrationTest extends ApiTestCase {
 		array $expected,
 		string $accountName = 'New account',
 		bool $autocreate = false,
-		string $creatorName = null
+		?string $creatorName = null
 	) {
 		$varHolder = null;
 		$this->prepareServices();
diff --git a/tests/phpunit/integration/Api/AbuseFilterApiTestTrait.php b/tests/phpunit/integration/Api/AbuseFilterApiTestTrait.php
index fadfdaa35..28fa51bd8 100644
--- a/tests/phpunit/integration/Api/AbuseFilterApiTestTrait.php
+++ b/tests/phpunit/integration/Api/AbuseFilterApiTestTrait.php
@@ -14,7 +14,7 @@ trait AbuseFilterApiTestTrait {
 	 * @param FilterEvaluator|null $ruleChecker
 	 * @return RuleCheckerFactory
 	 */
-	protected function getRuleCheckerFactory( FilterEvaluator $ruleChecker = null ): RuleCheckerFactory {
+	protected function getRuleCheckerFactory( ?FilterEvaluator $ruleChecker = null ): RuleCheckerFactory {
 		$factory = $this->createMock( RuleCheckerFactory::class );
 		if ( $ruleChecker !== null ) {
 			$factory->expects( $this->atLeastOnce() )
diff --git a/tests/phpunit/integration/EchoNotifierTest.php b/tests/phpunit/integration/EchoNotifierTest.php
index 1c69a7f9b..6fa9c6cb0 100644
--- a/tests/phpunit/integration/EchoNotifierTest.php
+++ b/tests/phpunit/integration/EchoNotifierTest.php
@@ -21,7 +21,7 @@ class EchoNotifierTest extends MediaWikiIntegrationTestCase {
 		'2' => 42,
 	];
 
-	private function getFilterLookup( int $userID = null ): FilterLookup {
+	private function getFilterLookup( ?int $userID = null ): FilterLookup {
 		$lookup = $this->createMock( FilterLookup::class );
 		$lookup->method( 'getFilter' )
 			->willReturnCallback( function ( $filter, $global ) use ( $userID ) {
diff --git a/tests/phpunit/integration/FilterRunnerTest.php b/tests/phpunit/integration/FilterRunnerTest.php
index 03921bdad..908e14bec 100644
--- a/tests/phpunit/integration/FilterRunnerTest.php
+++ b/tests/phpunit/integration/FilterRunnerTest.php
@@ -37,9 +37,9 @@ class FilterRunnerTest extends MediaWikiIntegrationTestCase {
 	 * @return FilterRunner
 	 */
 	private function getRunner(
-		ChangeTagger $changeTagger = null,
-		EditStashCache $cache = null,
-		VariableHolder $vars = null,
+		?ChangeTagger $changeTagger = null,
+		?EditStashCache $cache = null,
+		?VariableHolder $vars = null,
 		$group = 'default'
 	): FilterRunner {
 		$opts = new ServiceOptions(
diff --git a/tests/phpunit/unit/Consequences/Consequence/ThrottleTest.php b/tests/phpunit/unit/Consequences/Consequence/ThrottleTest.php
index 6a5b60ffd..fe00b8e62 100644
--- a/tests/phpunit/unit/Consequences/Consequence/ThrottleTest.php
+++ b/tests/phpunit/unit/Consequences/Consequence/ThrottleTest.php
@@ -29,12 +29,12 @@ class ThrottleTest extends MediaWikiUnitTestCase {
 
 	private function getThrottle(
 		array $throttleParams = [],
-		BagOStuff $cache = null,
+		?BagOStuff $cache = null,
 		bool $globalFilter = false,
-		UserIdentity $user = null,
-		Title $title = null,
-		UserEditTracker $editTracker = null,
-		string $ip = null
+		?UserIdentity $user = null,
+		?Title $title = null,
+		?UserEditTracker $editTracker = null,
+		?string $ip = null
 	) {
 		$specifier = new ActionSpecifier(
 			'some-action',
@@ -95,7 +95,7 @@ class ThrottleTest extends MediaWikiUnitTestCase {
 	/**
 	 * @dataProvider provideThrottle
 	 */
-	public function testExecute( Throttle $throttle, bool $shouldDisable, MockObject $cache = null ) {
+	public function testExecute( Throttle $throttle, bool $shouldDisable, ?MockObject $cache = null ) {
 		if ( $cache ) {
 			/** @var Throttle $wrapper */
 			$wrapper = TestingAccessWrapper::newFromObject( $throttle );
@@ -115,7 +115,7 @@ class ThrottleTest extends MediaWikiUnitTestCase {
 		string $ip,
 		Title $title,
 		UserIdentity $user,
-		UserEditTracker $editTracker = null
+		?UserEditTracker $editTracker = null
 	) {
 		$throttle = $this->getThrottle( [], null, false, $user, $title, $editTracker, $ip );
 		/** @var Throttle $throttleWrapper */
diff --git a/tests/phpunit/unit/Consequences/Consequence/WarnTest.php b/tests/phpunit/unit/Consequences/Consequence/WarnTest.php
index 7740f52d6..78fc56ca6 100644
--- a/tests/phpunit/unit/Consequences/Consequence/WarnTest.php
+++ b/tests/phpunit/unit/Consequences/Consequence/WarnTest.php
@@ -21,7 +21,7 @@ use Wikimedia\TestingAccessWrapper;
 class WarnTest extends MediaWikiUnitTestCase {
 	use ConsequenceGetMessageTestTrait;
 
-	private function getWarn( Parameters $params = null ): Warn {
+	private function getWarn( ?Parameters $params = null ): Warn {
 		return new Warn(
 			$params ?? $this->createMock( Parameters::class ),
 			'foo-bar-message',
diff --git a/tests/phpunit/unit/EditRevUpdaterTest.php b/tests/phpunit/unit/EditRevUpdaterTest.php
index de943cdad..2d3e1cbdf 100644
--- a/tests/phpunit/unit/EditRevUpdaterTest.php
+++ b/tests/phpunit/unit/EditRevUpdaterTest.php
@@ -42,9 +42,9 @@ class EditRevUpdaterTest extends MediaWikiUnitTestCase {
 	 * @return EditRevUpdater
 	 */
 	private function getUpdater(
-		IDatabase $localDB = null,
-		IDatabase $centralDB = null,
-		RevisionLookup $revLookup = null
+		?IDatabase $localDB = null,
+		?IDatabase $centralDB = null,
+		?RevisionLookup $revLookup = null
 	): EditRevUpdater {
 		$lbFactory = $this->createMock( LBFactory::class );
 		$lbFactory->method( 'getPrimaryDatabase' )
diff --git a/tests/phpunit/unit/FilterImporterTest.php b/tests/phpunit/unit/FilterImporterTest.php
index ecf733990..0cd0477cb 100644
--- a/tests/phpunit/unit/FilterImporterTest.php
+++ b/tests/phpunit/unit/FilterImporterTest.php
@@ -40,9 +40,9 @@ class FilterImporterTest extends MediaWikiUnitTestCase {
 	 * @return FilterImporter
 	 */
 	private function getImporter(
-		array $groups = null,
-		bool $isCentral = null,
-		array $actions = null
+		?array $groups = null,
+		?bool $isCentral = null,
+		?array $actions = null
 	): FilterImporter {
 		$actions = array_fill_keys( $actions ?? [ 'warn', 'disallow', 'block' ], true );
 		$registry = new ConsequencesRegistry(
diff --git a/tests/phpunit/unit/FilterLookupTest.php b/tests/phpunit/unit/FilterLookupTest.php
index 8db8ac539..c860162a9 100644
--- a/tests/phpunit/unit/FilterLookupTest.php
+++ b/tests/phpunit/unit/FilterLookupTest.php
@@ -43,9 +43,9 @@ class FilterLookupTest extends MediaWikiUnitTestCase {
 	 * @return FilterLookup
 	 */
 	private function getLookup(
-		IDatabase $db = null,
+		?IDatabase $db = null,
 		$centralDB = false,
-		WANObjectCache $cache = null,
+		?WANObjectCache $cache = null,
 		bool $filterIsCentral = false
 	): FilterLookup {
 		$lb = $this->createMock( ILoadBalancer::class );
diff --git a/tests/phpunit/unit/FilterProfilerTest.php b/tests/phpunit/unit/FilterProfilerTest.php
index ed40784c5..acefb1b09 100644
--- a/tests/phpunit/unit/FilterProfilerTest.php
+++ b/tests/phpunit/unit/FilterProfilerTest.php
@@ -34,7 +34,7 @@ class FilterProfilerTest extends MediaWikiUnitTestCase {
 		'matches' => 0,
 	];
 
-	private function getFilterProfiler( LoggerInterface $logger = null ): FilterProfiler {
+	private function getFilterProfiler( ?LoggerInterface $logger = null ): FilterProfiler {
 		$options = [
 			'AbuseFilterConditionLimit' => 1000,
 			'AbuseFilterSlowFilterRuntimeLimit' => 500,
diff --git a/tests/phpunit/unit/FilterValidatorTest.php b/tests/phpunit/unit/FilterValidatorTest.php
index 2bf116219..5a6c80456 100644
--- a/tests/phpunit/unit/FilterValidatorTest.php
+++ b/tests/phpunit/unit/FilterValidatorTest.php
@@ -37,8 +37,8 @@ class FilterValidatorTest extends MediaWikiUnitTestCase {
 	 * @return FilterValidator
 	 */
 	private function getFilterValidator(
-		AbuseFilterPermissionManager $permissionManager = null,
-		FilterEvaluator $ruleChecker = null,
+		?AbuseFilterPermissionManager $permissionManager = null,
+		?FilterEvaluator $ruleChecker = null,
 		array $restrictions = [],
 		array $validFilterGroups = [ 'default' ]
 	): FilterValidator {
@@ -481,8 +481,8 @@ class FilterValidatorTest extends MediaWikiUnitTestCase {
 	public function testCheckAll(
 		AbstractFilter $newFilter,
 		?string $expectedError,
-		AbuseFilterPermissionManager $permissionManager = null,
-		FilterEvaluator $ruleChecker = null,
+		?AbuseFilterPermissionManager $permissionManager = null,
+		?FilterEvaluator $ruleChecker = null,
 		array $restrictions = [],
 		bool $isFatalError = false
 	) {
diff --git a/tests/phpunit/unit/Parser/ParserTestCase.php b/tests/phpunit/unit/Parser/ParserTestCase.php
index 5d7105a12..c816b2b9e 100644
--- a/tests/phpunit/unit/Parser/ParserTestCase.php
+++ b/tests/phpunit/unit/Parser/ParserTestCase.php
@@ -45,7 +45,7 @@ abstract class ParserTestCase extends MediaWikiUnitTestCase {
 	 * @param LoggerInterface|null $logger
 	 * @return FilterEvaluator
 	 */
-	protected function getParser( LoggerInterface $logger = null ) {
+	protected function getParser( ?LoggerInterface $logger = null ) {
 		// We're not interested in caching or logging; tests should call respectively setCache
 		// and setLogger if they want to test any of those.
 		$keywordsManager = new KeywordsManager( $this->createMock( AbuseFilterHookRunner::class ) );
diff --git a/tests/phpunit/unit/Variables/VariablesBlobStoreTest.php b/tests/phpunit/unit/Variables/VariablesBlobStoreTest.php
index 1fdeb3efd..dae65fa04 100644
--- a/tests/phpunit/unit/Variables/VariablesBlobStoreTest.php
+++ b/tests/phpunit/unit/Variables/VariablesBlobStoreTest.php
@@ -24,8 +24,8 @@ use Wikimedia\TestingAccessWrapper;
 class VariablesBlobStoreTest extends MediaWikiUnitTestCase {
 
 	private function getStore(
-		BlobStoreFactory $blobStoreFactory = null,
-		BlobStore $blobStore = null
+		?BlobStoreFactory $blobStoreFactory = null,
+		?BlobStore $blobStore = null
 	): VariablesBlobStore {
 		$manager = $this->createMock( VariablesManager::class );
 		$manager->method( 'dumpAllVars' )->willReturnCallback( static function ( VariableHolder $holder ) {
@@ -180,7 +180,7 @@ class VariablesBlobStoreTest extends MediaWikiUnitTestCase {
 	/**
 	 * @dataProvider provideVariables
 	 */
-	public function testRoundTrip( array $toStore, array $expected = null ) {
+	public function testRoundTrip( array $toStore, ?array $expected = null ) {
 		$blobStore = $this->getBlobStore();
 		$blobStoreFactory = $this->createMock( BlobStoreFactory::class );
 		$blobStoreFactory->method( 'newBlobStore' )->willReturn( $blobStore );
diff --git a/tests/phpunit/unit/Variables/VariablesManagerTest.php b/tests/phpunit/unit/Variables/VariablesManagerTest.php
index 9616e789c..455fd69ee 100644
--- a/tests/phpunit/unit/Variables/VariablesManagerTest.php
+++ b/tests/phpunit/unit/Variables/VariablesManagerTest.php
@@ -23,7 +23,7 @@ class VariablesManagerTest extends MediaWikiUnitTestCase {
 	 * @param LazyVariableComputer|null $lazyComputer
 	 * @return VariablesManager
 	 */
-	private function getManager( LazyVariableComputer $lazyComputer = null ): VariablesManager {
+	private function getManager( ?LazyVariableComputer $lazyComputer = null ): VariablesManager {
 		return new VariablesManager(
 			new KeywordsManager( $this->createMock( AbuseFilterHookRunner::class ) ),
 			$lazyComputer ?? $this->createMock( LazyVariableComputer::class )