diff --git a/typo3/sysext/install/Classes/Configuration/AbstractPreset.php b/typo3/sysext/install/Classes/Configuration/AbstractPreset.php
index 52b5bac0d79c0c99112025a161f1a4251621f826..b7eeb3c227c541943cd43d3ba58f07885d46711d 100644
--- a/typo3/sysext/install/Classes/Configuration/AbstractPreset.php
+++ b/typo3/sysext/install/Classes/Configuration/AbstractPreset.php
@@ -58,7 +58,7 @@ abstract class AbstractPreset implements PresetInterface
     /**
      * @param \TYPO3\CMS\Core\Configuration\ConfigurationManager $configurationManager
      */
-    public function __construct(ConfigurationManager $configurationManager = null)
+    public function __construct(?ConfigurationManager $configurationManager = null)
     {
         $this->configurationManager = $configurationManager ?: GeneralUtility::makeInstance(ConfigurationManager::class);
     }
diff --git a/typo3/sysext/install/Classes/ExtensionScanner/Php/GeneratorClassesResolver.php b/typo3/sysext/install/Classes/ExtensionScanner/Php/GeneratorClassesResolver.php
index 8f9dca59135ba8166064c31168f42d6773e6fe7d..75c2a0ee3d00b9c1fa2644a52c94c6caec0058ef 100644
--- a/typo3/sysext/install/Classes/ExtensionScanner/Php/GeneratorClassesResolver.php
+++ b/typo3/sysext/install/Classes/ExtensionScanner/Php/GeneratorClassesResolver.php
@@ -45,7 +45,7 @@ class GeneratorClassesResolver extends NodeVisitorAbstract
      */
     protected $builderFactory;
 
-    public function __construct(BuilderFactory $builderFactory = null)
+    public function __construct(?BuilderFactory $builderFactory = null)
     {
         $this->builderFactory = $builderFactory ?? new BuilderFactory();
     }
diff --git a/typo3/sysext/install/Classes/FolderStructure/DirectoryNode.php b/typo3/sysext/install/Classes/FolderStructure/DirectoryNode.php
index 22a202373208d8fc77c975b05ba30af611c92d95..bb2a8289a560e9dd2c5d19605a3c39f999794366 100644
--- a/typo3/sysext/install/Classes/FolderStructure/DirectoryNode.php
+++ b/typo3/sysext/install/Classes/FolderStructure/DirectoryNode.php
@@ -37,7 +37,7 @@ class DirectoryNode extends AbstractNode implements NodeInterface
      * @param NodeInterface $parent Parent object
      * @throws Exception\InvalidArgumentException
      */
-    public function __construct(array $structure, NodeInterface $parent = null)
+    public function __construct(array $structure, ?NodeInterface $parent = null)
     {
         if ($parent === null) {
             throw new InvalidArgumentException(
diff --git a/typo3/sysext/install/Classes/FolderStructure/FileNode.php b/typo3/sysext/install/Classes/FolderStructure/FileNode.php
index 2b1b0e21105666090d6f9a3aa10f1d6d5240b5a8..9bc3882eb58cffd1fea23381a8d49409892cb70f 100644
--- a/typo3/sysext/install/Classes/FolderStructure/FileNode.php
+++ b/typo3/sysext/install/Classes/FolderStructure/FileNode.php
@@ -41,7 +41,7 @@ class FileNode extends AbstractNode implements NodeInterface
      * @param NodeInterface $parent Parent object
      * @throws Exception\InvalidArgumentException
      */
-    public function __construct(array $structure, NodeInterface $parent = null)
+    public function __construct(array $structure, ?NodeInterface $parent = null)
     {
         if ($parent === null) {
             throw new InvalidArgumentException(
diff --git a/typo3/sysext/install/Classes/FolderStructure/LinkNode.php b/typo3/sysext/install/Classes/FolderStructure/LinkNode.php
index b011790caa18c13a2f950532ce79f0b9be31945f..d14b5702d418308f0393f3c9e1b1cca6fb5c9f4a 100644
--- a/typo3/sysext/install/Classes/FolderStructure/LinkNode.php
+++ b/typo3/sysext/install/Classes/FolderStructure/LinkNode.php
@@ -36,7 +36,7 @@ class LinkNode extends AbstractNode implements NodeInterface
      * @param NodeInterface $parent Parent object
      * @throws Exception\InvalidArgumentException
      */
-    public function __construct(array $structure, NodeInterface $parent = null)
+    public function __construct(array $structure, ?NodeInterface $parent = null)
     {
         if ($parent === null) {
             throw new InvalidArgumentException(
diff --git a/typo3/sysext/install/Classes/FolderStructure/NodeInterface.php b/typo3/sysext/install/Classes/FolderStructure/NodeInterface.php
index c3c1123b3906b34848a13ee03493d3f4fae3a7e0..cb33e63a133a97bed0054bcef8f55e9a06287359 100644
--- a/typo3/sysext/install/Classes/FolderStructure/NodeInterface.php
+++ b/typo3/sysext/install/Classes/FolderStructure/NodeInterface.php
@@ -28,7 +28,7 @@ interface NodeInterface
      * @param array $structure Structure
      * @param NodeInterface $parent Parent
      */
-    public function __construct(array $structure, NodeInterface $parent = null);
+    public function __construct(array $structure, ?NodeInterface $parent = null);
 
     /**
      * Get node name
diff --git a/typo3/sysext/install/Classes/FolderStructure/RootNode.php b/typo3/sysext/install/Classes/FolderStructure/RootNode.php
index 389fc2cf4adc1475c8b8fe4c545a8f0e88ff177d..d69f89d5fee6c7a25c2f4d466f1285eb660d4cc8 100644
--- a/typo3/sysext/install/Classes/FolderStructure/RootNode.php
+++ b/typo3/sysext/install/Classes/FolderStructure/RootNode.php
@@ -33,7 +33,7 @@ class RootNode extends DirectoryNode implements RootNodeInterface
      * @throws Exception\RootNodeException
      * @throws Exception\InvalidArgumentException
      */
-    public function __construct(array $structure, NodeInterface $parent = null)
+    public function __construct(array $structure, ?NodeInterface $parent = null)
     {
         if ($parent !== null) {
             throw new RootNodeException(
diff --git a/typo3/sysext/install/Classes/SystemEnvironment/ServerResponse/ContentSecurityPolicyHeader.php b/typo3/sysext/install/Classes/SystemEnvironment/ServerResponse/ContentSecurityPolicyHeader.php
index e86de5f5cf5e28e039995f9a3da5bb8cea7ae60b..7e8de587c77e16c16bfe612634994856c17e0a60 100644
--- a/typo3/sysext/install/Classes/SystemEnvironment/ServerResponse/ContentSecurityPolicyHeader.php
+++ b/typo3/sysext/install/Classes/SystemEnvironment/ServerResponse/ContentSecurityPolicyHeader.php
@@ -48,7 +48,7 @@ class ContentSecurityPolicyHeader
         return empty($this->directives);
     }
 
-    public function mitigatesCrossSiteScripting(string $fileName = null): bool
+    public function mitigatesCrossSiteScripting(?string $fileName = null): bool
     {
         $isSvg = str_ends_with($fileName ?? '', '.svg');
         $defaultSrc = isset($this->directives['default-src'])
diff --git a/typo3/sysext/install/Classes/UpgradeAnalysis/DocumentationFile.php b/typo3/sysext/install/Classes/UpgradeAnalysis/DocumentationFile.php
index e92287ccd033d510646293ce7c4a5c4d44c04897..d4c400c79adc889b207e729af35c37bef76c59ed 100644
--- a/typo3/sysext/install/Classes/UpgradeAnalysis/DocumentationFile.php
+++ b/typo3/sysext/install/Classes/UpgradeAnalysis/DocumentationFile.php
@@ -54,7 +54,7 @@ class DocumentationFile
      * @param Registry|null $registry
      * @param string $changelogDir
      */
-    public function __construct(Registry $registry = null, $changelogDir = '')
+    public function __construct(?Registry $registry = null, $changelogDir = '')
     {
         if ($registry === null) {
             $registry = new Registry();