diff --git a/composer.json b/composer.json
index ac53d17f..5928b83f 100644
--- a/composer.json
+++ b/composer.json
@@ -31,6 +31,7 @@
         "ibexa/doctrine-schema": "~6.0.x-dev",
         "ibexa/http-cache": "~6.0.x-dev",
         "ibexa/notifications": "~6.0.x-dev",
+        "ibexa/phpstan": "~6.0.x-dev",
         "ibexa/rector": "~6.0.x-dev",
         "ibexa/rest": "~6.0.x-dev",
         "ibexa/test-core": "~6.0.x-dev",
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index bee431fb..7366b226 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -1,6 +1,7 @@
 includes:
     - vendor/phpstan/phpstan-phpunit/extension.neon
     - vendor/phpstan/phpstan-symfony/extension.neon
+    - vendor/ibexa/phpstan/extension.neon
     - phpstan-baseline.neon
 
 parameters:
diff --git a/src/lib/FieldType/Mapper/UserAccountFieldValueFormMapper.php b/src/lib/FieldType/Mapper/UserAccountFieldValueFormMapper.php
index 271b4536..592b5a92 100644
--- a/src/lib/FieldType/Mapper/UserAccountFieldValueFormMapper.php
+++ b/src/lib/FieldType/Mapper/UserAccountFieldValueFormMapper.php
@@ -78,7 +78,7 @@ public function getModelTransformerForTranslation(FieldDefinition $fieldDefiniti
             static function (ApiUserValue $data): UserAccountFieldData {
                 return new UserAccountFieldData($data->login, null, $data->email, $data->enabled);
             },
-            static function (UserAccountFieldData $submittedData) use ($fieldDefinition) {
+            static function (UserAccountFieldData $submittedData) use ($fieldDefinition): ApiUserValue {
                 /** @var \Ibexa\Core\FieldType\User\Value $userValue */
                 $userValue = clone $fieldDefinition->defaultValue;
 
diff --git a/tests/lib/Event/FormActionEventTest.php b/tests/lib/Event/FormActionEventTest.php
index 8d608e63..83f36826 100644
--- a/tests/lib/Event/FormActionEventTest.php
+++ b/tests/lib/Event/FormActionEventTest.php
@@ -18,7 +18,7 @@ final class FormActionEventTest extends TestCase
 {
     public function testConstruct(): void
     {
-        $form = $this->createStub(FormInterface::class);
+        $form = self::createStub(FormInterface::class);
         $data = new stdClass();
         $clickedButton = 'fooButton';
         $options = ['languageCode' => 'eng-GB', 'foo' => 'bar'];
@@ -33,7 +33,7 @@ public function testConstruct(): void
     public function testEventDoesntHaveResponse(): void
     {
         $event = new FormActionEvent(
-            $this->createStub(FormInterface::class),
+            self::createStub(FormInterface::class),
             new stdClass(),
             'fooButton'
         );
@@ -44,7 +44,7 @@ public function testEventDoesntHaveResponse(): void
     public function testEventSetResponse(): void
     {
         $event = new FormActionEvent(
-            $this->createStub(FormInterface::class),
+            self::createStub(FormInterface::class),
             new stdClass(),
             'fooButton'
         );
@@ -63,7 +63,7 @@ public function testGetOption(): void
         $options = ['languageCode' => 'eng-GB', 'foo' => 'bar', 'obj' => $objectOption];
 
         $event = new FormActionEvent(
-            $this->createStub(FormInterface::class),
+            self::createStub(FormInterface::class),
             new stdClass(),
             'fooButton',
             $options
diff --git a/tests/lib/FieldType/DataTransformer/FieldValueTransformerTest.php b/tests/lib/FieldType/DataTransformer/FieldValueTransformerTest.php
index 94c6d591..cafebc34 100644
--- a/tests/lib/FieldType/DataTransformer/FieldValueTransformerTest.php
+++ b/tests/lib/FieldType/DataTransformer/FieldValueTransformerTest.php
@@ -32,7 +32,7 @@ public function testTransformNull(): void
 
     public function testTransform(): void
     {
-        $value = $this->createStub(Value::class);
+        $value = self::createStub(Value::class);
         $valueHash = ['lorem' => 'Lorem ipsum dolor...'];
 
         $fieldType = $this->createMock(FieldType::class);
@@ -49,7 +49,7 @@ public function testTransform(): void
 
     public function testReverseTransformNull(): void
     {
-        $emptyValue = $this->createStub(Value::class);
+        $emptyValue = self::createStub(Value::class);
 
         $fieldType = $this->createMock(FieldType::class);
         $fieldType
@@ -68,7 +68,7 @@ public function testReverseTransformNull(): void
     public function testReverseTransform(): void
     {
         $value = 'Lorem ipsum dolor...';
-        $expected = $this->createStub(Value::class);
+        $expected = self::createStub(Value::class);
 
         $fieldType = $this->createMock(FieldType::class);
         $fieldType
diff --git a/tests/lib/FieldType/FieldTypeFormMapperDispatcherTest.php b/tests/lib/FieldType/FieldTypeFormMapperDispatcherTest.php
index b239e0f1..fad6b492 100644
--- a/tests/lib/FieldType/FieldTypeFormMapperDispatcherTest.php
+++ b/tests/lib/FieldType/FieldTypeFormMapperDispatcherTest.php
@@ -42,7 +42,7 @@ public function testMapFieldValue(): void
             'fieldDefinition' => new FieldDefinition(['fieldTypeIdentifier' => 'first_type']),
         ]);
 
-        $formMock = $this->createStub(FormInterface::class);
+        $formMock = self::createStub(FormInterface::class);
 
         $this->fieldTypeAliasResolverMock
             ->method('resolveIdentifier')
diff --git a/tests/lib/FieldType/Mapper/BaseMapperTestCase.php b/tests/lib/FieldType/Mapper/BaseMapperTestCase.php
index 6a3e71c7..897a5af1 100644
--- a/tests/lib/FieldType/Mapper/BaseMapperTestCase.php
+++ b/tests/lib/FieldType/Mapper/BaseMapperTestCase.php
@@ -35,7 +35,7 @@ protected function setUp(): void
         $this->fieldTypeService = $this->createMock(FieldTypeService::class);
         $this->fieldTypeService
             ->method('getFieldType')
-            ->willReturn($this->createStub(FieldType::class));
+            ->willReturn(self::createStub(FieldType::class));
 
         $this->config = $this->createMock(FormConfigInterface::class);
         $this->fieldForm = $this->createMock(FormInterface::class);
@@ -43,7 +43,7 @@ protected function setUp(): void
         $formFactory
             ->expects(self::once())
             ->method('createBuilder')
-            ->willReturn($this->createStub(FormBuilder::class));
+            ->willReturn(self::createStub(FormBuilder::class));
 
         $this->config
             ->expects(self::once())
diff --git a/tests/lib/Form/EventSubscriber/FixUrlProtocolListenerTest.php b/tests/lib/Form/EventSubscriber/FixUrlProtocolListenerTest.php
index ece42b95..0821c727 100644
--- a/tests/lib/Form/EventSubscriber/FixUrlProtocolListenerTest.php
+++ b/tests/lib/Form/EventSubscriber/FixUrlProtocolListenerTest.php
@@ -29,7 +29,7 @@ final class FixUrlProtocolListenerTest extends TestCase
     #[DataProvider('provideUrlCases')]
     public function testUrlProtocolHandling(?string $inputData, ?string $expectedData, string $defaultProtocol = 'https'): void
     {
-        $form = $this->createStub(FormInterface::class);
+        $form = self::createStub(FormInterface::class);
         $listener = new FixUrlProtocolListener($defaultProtocol);
 
         $event = new FormEvent($form, $inputData);
diff --git a/tests/lib/Form/Processor/ContentFormProcessorTest.php b/tests/lib/Form/Processor/ContentFormProcessorTest.php
index aabb3682..9332edf8 100644
--- a/tests/lib/Form/Processor/ContentFormProcessorTest.php
+++ b/tests/lib/Form/Processor/ContentFormProcessorTest.php
@@ -108,10 +108,10 @@ public function testProcessPublish(
 
         // The deferred (async) redirect resolves its location from the content tree root config
         // and the location lookup.
-        $configResolver = $this->createStub(ConfigResolverInterface::class);
+        $configResolver = self::createStub(ConfigResolverInterface::class);
         $configResolver->method('getParameter')->willReturn(self::TREE_ROOT_LOCATION_ID);
 
-        $locationService = $this->createStub(LocationService::class);
+        $locationService = self::createStub(LocationService::class);
         $locationService->method('loadLocation')->willReturn(
             new Location([
                 'id' => self::TREE_ROOT_LOCATION_ID,
@@ -242,16 +242,16 @@ private function createDraft(?int $mainLocationId, int $status): Content
             'status' => $status,
         ]);
 
-        $versionInfo = $this->createStub(VersionInfo::class);
+        $versionInfo = self::createStub(VersionInfo::class);
         $versionInfo->method('getInitialLanguage')->willReturn(
             new Language(['languageCode' => self::LANGUAGE_CODE])
         );
         $versionInfo->method('getContentInfo')->willReturn($contentInfo);
 
-        $draft = $this->createStub(Content::class);
+        $draft = self::createStub(Content::class);
         $draft->method('getVersionInfo')->willReturn($versionInfo);
         $draft->method('getContentInfo')->willReturn($contentInfo);
-        $draft->method('getContentType')->willReturn($this->createStub(ContentType::class));
+        $draft->method('getContentType')->willReturn(self::createStub(ContentType::class));
 
         return $draft;
     }
@@ -265,7 +265,7 @@ private function createPublishedContent(): Content
             'status' => ContentInfo::STATUS_PUBLISHED,
         ]);
 
-        $publishedContent = $this->createStub(Content::class);
+        $publishedContent = self::createStub(Content::class);
         $publishedContent->method('getContentInfo')->willReturn($contentInfo);
         $publishedContent->method('getId')->willReturn(self::CONTENT_ID);
 
@@ -293,13 +293,13 @@ private function createCreateData(): ContentCreateData
      */
     private function createForm(?string $redirectUrlAfterPublish = null): FormInterface
     {
-        $formConfig = $this->createStub(FormConfigInterface::class);
+        $formConfig = self::createStub(FormConfigInterface::class);
         $formConfig->method('getOption')->willReturn(self::LANGUAGE_CODE);
 
-        $redirectUrlField = $this->createStub(FormInterface::class);
+        $redirectUrlField = self::createStub(FormInterface::class);
         $redirectUrlField->method('getData')->willReturn($redirectUrlAfterPublish);
 
-        $form = $this->createStub(FormInterface::class);
+        $form = self::createStub(FormInterface::class);
         $form->method('getConfig')->willReturn($formConfig);
         $form->method('offsetGet')->willReturn($redirectUrlField);
 
diff --git a/tests/lib/Validator/Constraints/PasswordTest.php b/tests/lib/Validator/Constraints/PasswordTest.php
index f7607ef3..2e4d9043 100644
--- a/tests/lib/Validator/Constraints/PasswordTest.php
+++ b/tests/lib/Validator/Constraints/PasswordTest.php
@@ -47,7 +47,7 @@ public function testGetTargets(): void
 
     public function testNamedArguments(): void
     {
-        $contentType = $this->createStub(ContentType::class);
+        $contentType = self::createStub(ContentType::class);
         $payload = new \stdClass();
 
         $constraint = new Password(
diff --git a/tests/lib/Validator/Constraints/PasswordValidatorTest.php b/tests/lib/Validator/Constraints/PasswordValidatorTest.php
index 8971bf83..dbc6995f 100644
--- a/tests/lib/Validator/Constraints/PasswordValidatorTest.php
+++ b/tests/lib/Validator/Constraints/PasswordValidatorTest.php
@@ -54,15 +54,15 @@ public function testValidateShouldBeSkipped(mixed $value): void
     public function testValid(): void
     {
         $password = 'pass';
-        $contentType = $this->createStub(ContentType::class);
+        $contentType = self::createStub(ContentType::class);
 
         $this->userService
             ->expects(self::once())
             ->method('validatePassword')
-            ->willReturnCallback(function ($actualPassword, $actualContext) use ($password, $contentType): array {
-                $this->assertEquals($password, $actualPassword);
-                $this->assertInstanceOf(PasswordValidationContext::class, $actualContext);
-                $this->assertSame($contentType, $actualContext->contentType);
+            ->willReturnCallback(static function ($actualPassword, $actualContext) use ($password, $contentType): array {
+                self::assertEquals($password, $actualPassword);
+                self::assertInstanceOf(PasswordValidationContext::class, $actualContext);
+                self::assertSame($contentType, $actualContext->contentType);
 
                 return [];
             });
@@ -76,7 +76,7 @@ public function testValid(): void
 
     public function testInvalid(): void
     {
-        $contentType = $this->createStub(ContentType::class);
+        $contentType = self::createStub(ContentType::class);
         $password = 'pass';
         $errorParameter = 'foo';
         $errorMessage = 'error';
@@ -84,10 +84,10 @@ public function testInvalid(): void
         $this->userService
             ->expects(self::once())
             ->method('validatePassword')
-            ->willReturnCallback(function ($actualPassword, $actualContext) use ($password, $contentType, $errorMessage, $errorParameter): array {
-                $this->assertEquals($password, $actualPassword);
-                $this->assertInstanceOf(PasswordValidationContext::class, $actualContext);
-                $this->assertSame($contentType, $actualContext->contentType);
+            ->willReturnCallback(static function ($actualPassword, $actualContext) use ($password, $contentType, $errorMessage, $errorParameter): array {
+                self::assertEquals($password, $actualPassword);
+                self::assertInstanceOf(PasswordValidationContext::class, $actualContext);
+                self::assertSame($contentType, $actualContext->contentType);
 
                 return [
                     new ValidationError($errorMessage, null, ['%foo%' => $errorParameter]),
diff --git a/tests/lib/Validator/Constraints/UserAccountPasswordTest.php b/tests/lib/Validator/Constraints/UserAccountPasswordTest.php
index 7fa71007..f8641418 100644
--- a/tests/lib/Validator/Constraints/UserAccountPasswordTest.php
+++ b/tests/lib/Validator/Constraints/UserAccountPasswordTest.php
@@ -40,7 +40,7 @@ public function testGetTargets(): void
 
     public function testNamedArguments(): void
     {
-        $contentType = $this->createStub(ContentType::class);
+        $contentType = self::createStub(ContentType::class);
 
         $constraint = new UserAccountPassword(contentType: $contentType);
 
diff --git a/tests/lib/Validator/Constraints/UserAccountPasswordValidatorTest.php b/tests/lib/Validator/Constraints/UserAccountPasswordValidatorTest.php
index 73633125..abedc535 100644
--- a/tests/lib/Validator/Constraints/UserAccountPasswordValidatorTest.php
+++ b/tests/lib/Validator/Constraints/UserAccountPasswordValidatorTest.php
@@ -63,15 +63,15 @@ public static function dataProviderForValidateNotSupportedValueType(): array
     public function testValid(): void
     {
         $userAccount = new UserAccountFieldData('user', 'pass', 'user@ibexa.co');
-        $contentType = $this->createStub(ContentType::class);
+        $contentType = self::createStub(ContentType::class);
 
         $this->userService
             ->expects(self::once())
             ->method('validatePassword')
-            ->willReturnCallback(function ($actualPassword, $actualContext) use ($userAccount, $contentType): array {
-                $this->assertEquals($userAccount->password, $actualPassword);
-                $this->assertInstanceOf(PasswordValidationContext::class, $actualContext);
-                $this->assertSame($contentType, $actualContext->contentType);
+            ->willReturnCallback(static function ($actualPassword, $actualContext) use ($userAccount, $contentType): array {
+                self::assertEquals($userAccount->password, $actualPassword);
+                self::assertInstanceOf(PasswordValidationContext::class, $actualContext);
+                self::assertSame($contentType, $actualContext->contentType);
 
                 return [];
             });
@@ -85,7 +85,7 @@ public function testValid(): void
 
     public function testInvalid(): void
     {
-        $contentType = $this->createStub(ContentType::class);
+        $contentType = self::createStub(ContentType::class);
         $userAccount = new UserAccountFieldData('user', 'pass', 'user@ibexa.co');
         $errorParameter = 'foo';
         $errorMessage = 'error';
@@ -93,10 +93,10 @@ public function testInvalid(): void
         $this->userService
             ->expects(self::once())
             ->method('validatePassword')
-            ->willReturnCallback(function ($actualPassword, $actualContext) use ($userAccount, $contentType, $errorMessage, $errorParameter): array {
-                $this->assertEquals($userAccount->password, $actualPassword);
-                $this->assertInstanceOf(PasswordValidationContext::class, $actualContext);
-                $this->assertSame($contentType, $actualContext->contentType);
+            ->willReturnCallback(static function ($actualPassword, $actualContext) use ($userAccount, $contentType, $errorMessage, $errorParameter): array {
+                self::assertEquals($userAccount->password, $actualPassword);
+                self::assertInstanceOf(PasswordValidationContext::class, $actualContext);
+                self::assertSame($contentType, $actualContext->contentType);
 
                 return [
                     new ValidationError($errorMessage, null, ['%foo%' => $errorParameter]),