diff --git a/openapi_jsonapi.info.yml b/openapi_jsonapi.info.yml
index 6b5d94f..6d4973e 100644
--- a/openapi_jsonapi.info.yml
+++ b/openapi_jsonapi.info.yml
@@ -2,7 +2,7 @@ name: OpenAPI JSON:API
 description: OpenAPI support for the JSON:API module.
 type: module
 package: Web Services
-core_version_requirement: ^10 || ^11
+core_version_requirement: ^10.1 || ^11 || ^12
 dependencies:
   - openapi:openapi
   - schemata:schemata
diff --git a/src/Plugin/openapi/OpenApiGenerator/JsonApiGenerator.php b/src/Plugin/openapi/OpenApiGenerator/JsonApiGenerator.php
index 7185ce2..99aa8f3 100644
--- a/src/Plugin/openapi/OpenApiGenerator/JsonApiGenerator.php
+++ b/src/Plugin/openapi/OpenApiGenerator/JsonApiGenerator.php
@@ -645,7 +645,7 @@ class JsonApiGenerator extends OpenApiGeneratorBase {
   /**
    * {@inheritdoc}
    */
-  protected function getEntityResponsesJsonApi($entity_type_id, $method, $bundle_name, $route_name, Route $route = NULL) {
+  protected function getEntityResponsesJsonApi($entity_type_id, $method, $bundle_name, $route_name, ?Route $route = NULL) {
     $route_type = $this->getRoutTypeFromName($route_name);
     if ($route_type === 'collection') {
       if ($method === 'get') {
@@ -702,7 +702,7 @@ class JsonApiGenerator extends OpenApiGeneratorBase {
       else {
         // Fake a route name that will yield the expected results for the related
         // responses.
-        $target_route_name = Routes::getRouteName($target_resource_type, $is_multiple ? 'collection' : 'individual');
+        $target_route_name = JsonApiRoutes::getRouteName($target_resource_type, $is_multiple ? 'collection' : 'individual');
         return $this->getEntityResponsesJsonApi(
           $target_resource_type->getEntityTypeId(),
           $method,
diff --git a/tests/src/Functional/RequestTestJsonapi.php b/tests/src/Functional/RequestTestJsonapi.php
index 16bcde2..c18b0ef 100644
--- a/tests/src/Functional/RequestTestJsonapi.php
+++ b/tests/src/Functional/RequestTestJsonapi.php
@@ -2,6 +2,9 @@
 
 namespace Drupal\Tests\openapi_jsonapi\Functional;
 
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;
+use PHPUnit\Framework\Attributes\DataProvider;
 use Drupal\Tests\openapi\Functional\RequestTestBase;
 
 /**
@@ -9,6 +12,8 @@ use Drupal\Tests\openapi\Functional\RequestTestBase;
  *
  * @group openapi_jsonapi
  */
+#[Group('openapi_jsonapi')]
+#[RunTestsInSeparateProcesses]
 final class RequestTestJsonapi extends RequestTestBase {
 
   /**
@@ -46,6 +51,7 @@ final class RequestTestJsonapi extends RequestTestBase {
    *
    * @dataProvider providerRequestTypes
    */
+  #[DataProvider('providerRequestTypes')]
   public function testRequests($api_module, $options = []) {
     $this->requestOpenApiJson($api_module, $options);
   }
diff --git a/tests/src/Kernel/JsonApiGeneratorTest.php b/tests/src/Kernel/JsonApiGeneratorTest.php
index 7675396..94d6e9f 100644
--- a/tests/src/Kernel/JsonApiGeneratorTest.php
+++ b/tests/src/Kernel/JsonApiGeneratorTest.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\Tests\openapi_jsonapi\Kernel;
 
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;
 use Drupal\KernelTests\KernelTestBase;
 use Drupal\openapi_test\Entity\OpenApiTestEntityType;
 
@@ -10,6 +12,8 @@ use Drupal\openapi_test\Entity\OpenApiTestEntityType;
  *
  * @group openapi_jsonapi
  */
+#[Group('openapi_jsonapi')]
+#[RunTestsInSeparateProcesses]
 final class JsonApiGeneratorTest extends KernelTestBase {
 
   /**