diff --git a/Tests/Functional/Fixtures/Frontend/Hook/ImplementingInterface.php b/Tests/Functional/Fixtures/Frontend/Hook/ImplementingInterface.php
index d7b7f22..df9d484 100644
--- a/Tests/Functional/Fixtures/Frontend/Hook/ImplementingInterface.php
+++ b/Tests/Functional/Fixtures/Frontend/Hook/ImplementingInterface.php
@@ -23,11 +23,12 @@
 
 namespace Sinso\Variables\Tests\Functional\Fixtures\Frontend\Hook;
 
+use Sinso\Variables\Domain\Model\MarkerCollection;
 use Sinso\Variables\Hooks\MarkersProcessorInterface;
 
 class ImplementingInterface implements MarkersProcessorInterface
 {
-    public function postProcessMarkers(array &$markers)
+    public function postProcessMarkers(MarkerCollection $markers): void
     {
         $markers['{{MARKER1}}']['replacement'] = 'Modified by hook';
     }
diff --git a/Tests/Functional/Frontend/AbstractProcessesMarkersTest.php b/Tests/Functional/Frontend/AbstractProcessesMarkersTest.php
index 332e646..299a93f 100644
--- a/Tests/Functional/Frontend/AbstractProcessesMarkersTest.php
+++ b/Tests/Functional/Frontend/AbstractProcessesMarkersTest.php
@@ -28,11 +28,11 @@
 
 abstract class AbstractProcessesMarkersTest extends FunctionalTestCase
 {
-    protected array $testExtensionsToLoad = [
+    protected $testExtensionsToLoad = [
         'typo3conf/ext/variables',
     ];
 
-    protected array $pathsToLinkInTestInstance = [
+    protected $pathsToLinkInTestInstance = [
         'typo3conf/ext/variables/Tests/Functional/Fixtures/Frontend/Sites/' => 'typo3conf/sites',
     ];
 
diff --git a/Tests/Functional/Frontend/BreaksOnInvalidHookTest.php b/Tests/Functional/Frontend/BreaksOnInvalidHookTest.php
index 25cd61f..319267b 100644
--- a/Tests/Functional/Frontend/BreaksOnInvalidHookTest.php
+++ b/Tests/Functional/Frontend/BreaksOnInvalidHookTest.php
@@ -30,7 +30,7 @@
  */
 class BreaksOnInvalidHookTest extends AbstractProcessesMarkersTest
 {
-    protected array $configurationToUseInTestInstance = [
+    protected $configurationToUseInTestInstance = [
         'EXTCONF' => [
             'variables' => [
                 'postProcessMarkers' => [
diff --git a/Tests/Functional/Frontend/ProcessesMarkersHookTest.php b/Tests/Functional/Frontend/ProcessesMarkersHookTest.php
index 22f0d7c..5ca5f57 100644
--- a/Tests/Functional/Frontend/ProcessesMarkersHookTest.php
+++ b/Tests/Functional/Frontend/ProcessesMarkersHookTest.php
@@ -30,7 +30,7 @@
  */
 class ProcessesMarkersHookTest extends AbstractProcessesMarkersTest
 {
-    protected array $configurationToUseInTestInstance = [
+    protected $configurationToUseInTestInstance = [
         'EXTCONF' => [
             'variables' => [
                 'postProcessMarkers' => [