diff --git a/composer.json b/composer.json
index ac3b332..86c2628 100644
--- a/composer.json
+++ b/composer.json
@@ -11,12 +11,12 @@
         }
     ],
     "require": {
-        "php": "^7.2|8.0.*|8.1.*|8.2.*|8.3.*",
+        "php": ">= 8.1",
         "ext-dom": "*",
         "ext-xml": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.5"
+        "phpunit/phpunit": "^10.5.58"
     },
     "autoload": {
         "psr-4": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 0fb736f..42d3986 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,25 +1,22 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit backupGlobals="false"
-         backupStaticAttributes="false"
-         colors="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         processIsolation="false"
-         stopOnFailure="false"
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
          bootstrap="vendor/autoload.php"
+         cacheResultFile=".phpunit.cache/test-results"
+         failOnDeprecation="true"
+         failOnPhpunitDeprecation="true"
+         displayDetailsOnTestsThatTriggerDeprecations="true"
+         displayDetailsOnPhpunitDeprecations="true"
 >
+    <source ignoreSuppressionOfDeprecations="true">
+        <include>
+            <directory>src</directory>
+        </include>
+    </source>
 
     <testsuites>
         <testsuite name="default">
-            <directory>tests/*</directory>
+            <directory>tests</directory>
         </testsuite>
     </testsuites>
-
-    <!-- Filter for code coverage -->
-    <filter>
-        <whitelist processUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">src/</directory>
-        </whitelist>
-    </filter>
 </phpunit>
diff --git a/tests/Webfactory/Dom/Test/BaseParsingHelperTest.php b/tests/Webfactory/Dom/Test/BaseParsingHelperTest.php
index fb9a03f..2269ac4 100644
--- a/tests/Webfactory/Dom/Test/BaseParsingHelperTest.php
+++ b/tests/Webfactory/Dom/Test/BaseParsingHelperTest.php
@@ -12,9 +12,9 @@
 use Webfactory\Dom\Exception\EmptyXMLStringException;
 use Webfactory\Dom\Exception\ParsingException;
 
-class BaseParsingHelperTest extends ParsingHelperTest
+class BaseParsingHelperTest extends ParsingHelperTestCase
 {
-    protected function createParsingHelper()
+    protected function createParsingHelper(): BaseParsingHelper
     {
         return new BaseParsingHelper();
     }
@@ -22,7 +22,7 @@ protected function createParsingHelper()
     /**
      * @test
      */
-    public function entireDocumentIsPreserved()
+    public function entireDocumentIsPreserved(): void
     {
         /* Ein gesamtes Dokument, mit default-Namespace und NS-Deklarationen in unterschiedlichen Scopes */
         $entireDocument = <<<XML
@@ -46,7 +46,7 @@ public function entireDocumentIsPreserved()
     /**
      * @test
      */
-    public function parseFragment()
+    public function parseFragment(): void
     {
         // Unterschiedliche Fragmente mit verschiedenen NS-Deklarationen
         $this->readDumpAssertFragment('<tag>Foo</tag>');
@@ -58,7 +58,7 @@ public function parseFragment()
     /**
      * @test
      */
-    public function defaultNamespaceOnInnerElementIsNotPrefixed()
+    public function defaultNamespaceOnInnerElementIsNotPrefixed(): void
     {
         $this->markTestSkipped(
             'Pending bugs in PHP: https://bugs.php.net/bug.php?id=47530, https://bugs.php.net/bug.php?id=55294'
@@ -95,7 +95,7 @@ public function defaultNamespaceOnInnerElementIsNotPrefixed()
     /**
      * @test
      */
-    public function parseFragmentWithUnknownNamespaceDecl()
+    public function parseFragmentWithUnknownNamespaceDecl(): void
     {
         $this->expectException(ParsingException::class);
         $this->readDumpAssertFragment('<foo:tag>xxx</foo:tag>');
@@ -104,7 +104,7 @@ public function parseFragmentWithUnknownNamespaceDecl()
     /**
      * @test
      */
-    public function parseDocumentWithUnknownNamespaceDecl()
+    public function parseDocumentWithUnknownNamespaceDecl(): void
     {
         $this->expectException(ParsingException::class);
         $document = $this->parser->parseDocument('<root><foo:fail>failme</foo:fail></root>');
@@ -113,7 +113,7 @@ public function parseDocumentWithUnknownNamespaceDecl()
     /**
      * @test
      */
-    public function parseFragmentWithImplicitNamespaceDecl()
+    public function parseFragmentWithImplicitNamespaceDecl(): void
     {
         $this->parser->addImplicitNamespace('foo', 'urn:some-namespace-uri');
         $this->readDumpAssertFragment('<foo:tag>xxx</foo:tag>');
@@ -122,7 +122,7 @@ public function parseFragmentWithImplicitNamespaceDecl()
     /**
      * @test
      */
-    public function parseFragmentImplicitNamespaceOnLoadIsAddedOnDump()
+    public function parseFragmentImplicitNamespaceOnLoadIsAddedOnDump(): void
     {
         $this->readDumpAssertFragment(
             '<foo:tag>xxx</foo:tag>',
@@ -152,7 +152,7 @@ public function parseFragmentImplicitNamespaceOnLoadIsAddedOnDump()
     /**
      * @test
      */
-    public function parseFragmentWithImplicitNamespaceOnDump()
+    public function parseFragmentWithImplicitNamespaceOnDump(): void
     {
         // Wenn der Namespace schon deklariert ist, entfällt die erneute Angabe
         $this->readDumpAssertFragment(
@@ -166,7 +166,7 @@ public function parseFragmentWithImplicitNamespaceOnDump()
     /**
      * @test
      */
-    public function implicitNamespaceDeclDoesNotInterfereWithFragment()
+    public function implicitNamespaceDeclDoesNotInterfereWithFragment(): void
     {
         $this->parser->addImplicitNamespace('foo', 'urn:some-namespace-uri');
         $this->readDumpAssertFragment('<foo:tag xmlns:foo="urn:some-other-uri">xxx</foo:tag>');
@@ -175,7 +175,7 @@ public function implicitNamespaceDeclDoesNotInterfereWithFragment()
     /**
      * @test
      */
-    public function implicitNamespaceDeclOnDumpMismatchesFragment()
+    public function implicitNamespaceDeclOnDumpMismatchesFragment(): void
     {
         $this->readDumpAssertFragment(
             '<foo:tag xmlns:foo="urn:some-namespace-uri">xxx</foo:tag>',
@@ -194,7 +194,7 @@ public function implicitNamespaceDeclOnDumpMismatchesFragment()
     /**
      * @test
      */
-    public function implicitNamespaceDeclDoesNotChangePrefix()
+    public function implicitNamespaceDeclDoesNotChangePrefix(): void
     {
         // Eine Deklaration über ein anderes Prefix ändert nichts - Prefixe werden nicht umgeschrieben
         $this->readDumpAssertFragment(
@@ -207,7 +207,7 @@ public function implicitNamespaceDeclDoesNotChangePrefix()
     /**
      * @test
      */
-    public function partialDumpCarriesOverNamespaceDeclaration()
+    public function partialDumpCarriesOverNamespaceDeclaration(): void
     {
         $document = $this->parser->parseDocument('<root xmlns="urn:test"><foo>test</foo></root>');
         $this->assertEquals(
@@ -219,7 +219,7 @@ public function partialDumpCarriesOverNamespaceDeclaration()
     /**
      * @test
      */
-    public function xPathExpressionAndNodeListDump()
+    public function xPathExpressionAndNodeListDump(): void
     {
         $this->parser->addImplicitNamespace('foo', 'urn:some-uri');
         $f = $this->parser->parseFragment(
@@ -239,7 +239,7 @@ public function xPathExpressionAndNodeListDump()
     /**
      * @test
      */
-    public function parsingEmptyDocumentFails()
+    public function parsingEmptyDocumentFails(): void
     {
         $this->expectException(EmptyXMLStringException::class);
         $this->parser->parseDocument('');
@@ -248,7 +248,7 @@ public function parsingEmptyDocumentFails()
     /**
      * @test
      */
-    public function parsingEmptyFragmentFails()
+    public function parsingEmptyFragmentFails(): void
     {
         $this->expectException(EmptyXMLStringException::class);
         $this->parser->parseFragment('');
@@ -257,7 +257,7 @@ public function parsingEmptyFragmentFails()
     /**
      * @test
      */
-    public function invalidCharactersAreTolerated()
+    public function invalidCharactersAreTolerated(): void
     {
         $fragment = "<root>\x0b\t\n</root>";
 
diff --git a/tests/Webfactory/Dom/Test/HTMLParsingHelperTest.php b/tests/Webfactory/Dom/Test/HTMLParsingHelperTestCase.php
similarity index 75%
rename from tests/Webfactory/Dom/Test/HTMLParsingHelperTest.php
rename to tests/Webfactory/Dom/Test/HTMLParsingHelperTestCase.php
index 429eacf..ba62fc5 100644
--- a/tests/Webfactory/Dom/Test/HTMLParsingHelperTest.php
+++ b/tests/Webfactory/Dom/Test/HTMLParsingHelperTestCase.php
@@ -8,12 +8,12 @@
 
 namespace Webfactory\Dom\Test;
 
-abstract class HTMLParsingHelperTest extends ParsingHelperTest
+abstract class HTMLParsingHelperTestCase extends ParsingHelperTestCase
 {
     /**
      * @test
      */
-    public function scriptWithCDataIsPreserved()
+    public function scriptWithCDataIsPreserved(): void
     {
         $this->readDumpAssertFragment('
             <script type="text/javascript" xml:space="preserve">
@@ -27,7 +27,7 @@ public function scriptWithCDataIsPreserved()
     /**
      * @test
      */
-    public function esiTagIsPreserved()
+    public function esiTagIsPreserved(): void
     {
         $this->readDumpAssertFragment('<p>Test <esi:include foo="bar"/></p>');
     }
@@ -35,7 +35,7 @@ public function esiTagIsPreserved()
     /**
      * @test
      */
-    public function esiTagWithXMLSpecialCharsIsPreserved()
+    public function esiTagWithXMLSpecialCharsIsPreserved(): void
     {
         $this->readDumpAssertFragment('<p>Test <esi:include foo="http://foo.bar?one=two&three=four"/></p>');
     }
diff --git a/tests/Webfactory/Dom/Test/ParsingHelperTest.php b/tests/Webfactory/Dom/Test/ParsingHelperTestCase.php
similarity index 93%
rename from tests/Webfactory/Dom/Test/ParsingHelperTest.php
rename to tests/Webfactory/Dom/Test/ParsingHelperTestCase.php
index cb59de0..6a20e5f 100644
--- a/tests/Webfactory/Dom/Test/ParsingHelperTest.php
+++ b/tests/Webfactory/Dom/Test/ParsingHelperTestCase.php
@@ -10,7 +10,7 @@
 
 use PHPUnit\Framework\TestCase;
 
-abstract class ParsingHelperTest extends TestCase
+abstract class ParsingHelperTestCase extends TestCase
 {
     /** @var \Webfactory\Dom\BaseParsingHelper */
     protected $parser;
@@ -27,7 +27,7 @@ protected function readDumpAssertFragment(
         $result = null,
         $declaredNamespacesInDump = null,
         $declaredNamespacesInRead = null
-    ) {
+    ): void {
         if (!$result) {
             $result = $fragment;
         }
diff --git a/tests/Webfactory/Dom/Test/PolyglotHTML5ParsingHelperTest.php b/tests/Webfactory/Dom/Test/PolyglotHTML5ParsingHelperTest.php
index e2a58b0..0e668e2 100644
--- a/tests/Webfactory/Dom/Test/PolyglotHTML5ParsingHelperTest.php
+++ b/tests/Webfactory/Dom/Test/PolyglotHTML5ParsingHelperTest.php
@@ -10,9 +10,9 @@
 
 use Webfactory\Dom\PolyglotHTML5ParsingHelper;
 
-class PolyglotHTML5ParsingHelperTest extends HTMLParsingHelperTest
+class PolyglotHTML5ParsingHelperTest extends HTMLParsingHelperTestCase
 {
-    protected function createParsingHelper()
+    protected function createParsingHelper(): PolyglotHTML5ParsingHelper
     {
         return new PolyglotHTML5ParsingHelper();
     }
@@ -20,7 +20,7 @@ protected function createParsingHelper()
     /**
      * @test
      */
-    public function voidTagsArePreservedWhileEmptyTagsAreExpanded()
+    public function voidTagsArePreservedWhileEmptyTagsAreExpanded(): void
     {
         $this->readDumpAssertFragment(
             '<area/><base/><br/><col/><command/><embed/><hr/><img/><input/><keygen/><link/><meta/><param/><source/>'
@@ -32,7 +32,7 @@ public function voidTagsArePreservedWhileEmptyTagsAreExpanded()
     /**
      * @test
      */
-    public function htmlEntitiesSupportedAsConvenience()
+    public function htmlEntitiesSupportedAsConvenience(): void
     {
         // webfactory Case 12739,
         // http://dev.w3.org/html5/html-xhtml-author-guide/#named-entity-references
@@ -56,7 +56,7 @@ public function htmlEntitiesSupportedAsConvenience()
     /**
      * @test
      */
-    public function svgNamespaceIsNotReconciled()
+    public function svgNamespaceIsNotReconciled(): void
     {
         /*
          * libxml2 will attempt (under which circumstances?) to reconciliate namespace declarations, that is, find
@@ -95,7 +95,7 @@ public function svgNamespaceIsNotReconciled()
      * @test
      * @dataProvider provideXpathForDocuments
      */
-    public function xpathParseDocument($xml, $xpathExpression)
+    public function xpathParseDocument($xml, $xpathExpression): void
     {
         $document = $this->parser->parseDocument($xml);
         $xpath = $this->parser->createXPath($document);
@@ -106,7 +106,7 @@ public function xpathParseDocument($xml, $xpathExpression)
         self::assertSame('test', $domNodeList[0]->textContent);
     }
 
-    public function provideXpathForDocuments()
+    public static function provideXpathForDocuments(): ?\Generator
     {
         yield 'HTML document that does not use a default namespace' => [
             /*
@@ -155,7 +155,7 @@ public function provideXpathForDocuments()
      * @test
      * @dataProvider provideXpathForFragments
      */
-    public function xpathParseFragment($xmlFragment, $xpathExpression)
+    public function xpathParseFragment($xmlFragment, $xpathExpression): void
     {
         $fragment = $this->parser->parseFragment($xmlFragment);
         $xpath = $this->parser->createXPath($fragment);
@@ -166,7 +166,7 @@ public function xpathParseFragment($xmlFragment, $xpathExpression)
         self::assertSame('test', $domNodeList[0]->textContent);
     }
 
-    public function provideXpathForFragments()
+    public static function provideXpathForFragments(): ?\Generator
     {
         yield 'default namespace assumed for fragments' => [
             /*
diff --git a/tests/Webfactory/Dom/Test/XHTML10ParsingHelperTest.php b/tests/Webfactory/Dom/Test/XHTML10ParsingHelperTest.php
index c00e794..ced606c 100644
--- a/tests/Webfactory/Dom/Test/XHTML10ParsingHelperTest.php
+++ b/tests/Webfactory/Dom/Test/XHTML10ParsingHelperTest.php
@@ -8,9 +8,9 @@
 
 namespace Webfactory\Dom\Test;
 
-class XHTML10ParsingHelperTest extends HTMLParsingHelperTest
+class XHTML10ParsingHelperTest extends HTMLParsingHelperTestCase
 {
-    protected function createParsingHelper()
+    protected function createParsingHelper(): \Webfactory\Dom\XHTML10ParsingHelper
     {
         return new \Webfactory\Dom\XHTML10ParsingHelper();
     }
@@ -18,7 +18,7 @@ protected function createParsingHelper()
     /**
      * @test
      */
-    public function entireDocumentIsPreserved()
+    public function entireDocumentIsPreserved(): void
     {
         $entireDocument = <<<XML
 <?xml version="1.0"?>
@@ -45,7 +45,7 @@ public function entireDocumentIsPreserved()
     /**
      * @test
      */
-    public function incompleteDocumentIsFixed()
+    public function incompleteDocumentIsFixed(): void
     {
         $missingNSDecl = <<<XML
 <?xml version="1.0"?>
@@ -66,7 +66,7 @@ public function incompleteDocumentIsFixed()
     /**
      * @test
      */
-    public function voidTagsArePreservedWhileEmptyTagsAreExpanded()
+    public function voidTagsArePreservedWhileEmptyTagsAreExpanded(): void
     {
         $this->readDumpAssertFragment(
             '<area/><base/><br/><col/><hr/><img/><input/><link/><meta/><param/>',