diff --git a/tests/src/FunctionalJavascript/NestedSetListBuilderTest.php b/tests/src/FunctionalJavascript/NestedSetListBuilderTest.php
index 2650ff4..30a572f 100644
--- a/tests/src/FunctionalJavascript/NestedSetListBuilderTest.php
+++ b/tests/src/FunctionalJavascript/NestedSetListBuilderTest.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Tests\nested_set\FunctionalJavascript;
 
+use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;
 use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
@@ -10,6 +11,7 @@ use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
 /**
  * Tests the nested set list builder.
  */
+#[RunTestsInSeparateProcesses]
 class NestedSetListBuilderTest extends WebDriverTestBase {
 
   /**
diff --git a/tests/src/Kernel/NestedSetItemOptionalTest.php b/tests/src/Kernel/NestedSetItemOptionalTest.php
index e7dd6f6..b03c7df 100644
--- a/tests/src/Kernel/NestedSetItemOptionalTest.php
+++ b/tests/src/Kernel/NestedSetItemOptionalTest.php
@@ -2,11 +2,13 @@
 
 namespace Drupal\Tests\nested_set\Kernel;
 
+use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;
 use Drupal\field\Entity\FieldConfig;
 
 /**
  * Tests the 'nested_set' field type.
  */
+#[RunTestsInSeparateProcesses]
 class NestedSetItemOptionalTest extends NestedSetKernelTestBase {
 
   /**
diff --git a/tests/src/Kernel/NestedSetItemTest.php b/tests/src/Kernel/NestedSetItemTest.php
index 4e40a15..cab382f 100644
--- a/tests/src/Kernel/NestedSetItemTest.php
+++ b/tests/src/Kernel/NestedSetItemTest.php
@@ -2,11 +2,13 @@
 
 namespace Drupal\Tests\nested_set\Kernel;
 
+use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;
 use Drupal\Core\Entity\EntityStorageException;
 
 /**
  * Tests the 'nested_set' field type.
  */
+#[RunTestsInSeparateProcesses]
 class NestedSetItemTest extends NestedSetKernelTestBase {
 
   /**
diff --git a/tests/src/Kernel/NestedSetItemTranslationTest.php b/tests/src/Kernel/NestedSetItemTranslationTest.php
index 1b1ab97..3d60a46 100644
--- a/tests/src/Kernel/NestedSetItemTranslationTest.php
+++ b/tests/src/Kernel/NestedSetItemTranslationTest.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Tests\nested_set\Kernel;
 
+use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\language\Entity\ConfigurableLanguage;
@@ -9,6 +10,7 @@ use Drupal\language\Entity\ConfigurableLanguage;
 /**
  * Tests the 'nested_set' field type with a translatable field.
  */
+#[RunTestsInSeparateProcesses]
 class NestedSetItemTranslationTest extends NestedSetKernelTestBase {
 
   /**
diff --git a/tests/src/Kernel/NestedSetKernelTestBase.php b/tests/src/Kernel/NestedSetKernelTestBase.php
index addbabc..8ee9085 100644
--- a/tests/src/Kernel/NestedSetKernelTestBase.php
+++ b/tests/src/Kernel/NestedSetKernelTestBase.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Tests\nested_set\Kernel;
 
+use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;
 use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Tests\field\Kernel\FieldKernelTestBase;
@@ -9,6 +10,7 @@ use Drupal\Tests\field\Kernel\FieldKernelTestBase;
 /**
  * Provides a base class for nested set kernel tests.
  */
+#[RunTestsInSeparateProcesses]
 class NestedSetKernelTestBase extends FieldKernelTestBase {
 
   /**