diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4c3515a..c826368 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -33,7 +33,7 @@ jobs:
           tools: composer:v2
 
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Download dependencies
         run: |
diff --git a/.github/workflows/static.yml b/.github/workflows/static.yml
index f9635cd..75f222d 100644
--- a/.github/workflows/static.yml
+++ b/.github/workflows/static.yml
@@ -13,7 +13,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: PHP-CS-Fixer
         uses: docker://oskarstark/php-cs-fixer-ga:2.16.4
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7d08045..030cae3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+
+## [3.1.2] - 2025-11-11
+
+- Allow PHPUnit > 9
+- Deprecate PhpUnitBackwardCompatibleTrait
+
 ## [3.1.1] - 2024-09-01
 
 - Switched to `httpbin.org` for tests now that its fixed. (Reverts [#56](https://github.com/php-http/client-integration-tests/pull/56))
diff --git a/composer.json b/composer.json
index 25ea7b6..784d11f 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,7 @@
     ],
     "require": {
         "php": "^7.4 || ^8.0",
-        "phpunit/phpunit": "^9.6.17",
+        "phpunit/phpunit": "^9.6.17 || ^10.0 || ^11.0 || ^12.0",
         "php-http/message": "^1.0 || ^2.0",
         "php-http/message-factory": "^1.0",
         "guzzlehttp/psr7": "^1.9 || ^2.0",
diff --git a/src/HttpAsyncClientTest.php b/src/HttpAsyncClientTest.php
index 0f13c05..1301ff6 100644
--- a/src/HttpAsyncClientTest.php
+++ b/src/HttpAsyncClientTest.php
@@ -3,6 +3,8 @@
 namespace Http\Client\Tests;
 
 use Http\Client\HttpAsyncClient;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\Group;
 
 abstract class HttpAsyncClientTest extends HttpBaseTest
 {
@@ -33,8 +35,8 @@ public function testSuccessiveCallMustUseResponseInterface()
     {
         $request = self::$messageFactory->createRequest(
             'GET',
-            $this->getUri(),
-            $this->defaultHeaders
+            self::getUri(),
+            self::$defaultHeaders
         );
 
         $promise = $this->httpAsyncClient->sendAsyncRequest($request);
@@ -61,7 +63,7 @@ public function testSuccessiveInvalidCallMustUseException()
         $request = self::$messageFactory->createRequest(
             'GET',
             $this->getInvalidUri(),
-            $this->defaultHeaders
+            self::$defaultHeaders
         );
 
         $promise = $this->httpAsyncClient->sendAsyncRequest($request);
@@ -90,6 +92,8 @@ public function testSuccessiveInvalidCallMustUseException()
      * @dataProvider requestProvider
      * @group        integration
      */
+    #[DataProvider('requestProvider')]
+    #[Group('integration')]
     public function testAsyncSendRequest($method, $uri, array $headers, $body)
     {
         if (null != $body) {
@@ -124,14 +128,15 @@ public function testAsyncSendRequest($method, $uri, array $headers, $body)
     }
 
     /**
-     * @group             integration
+     * @group integration
      */
+    #[Group('integration')]
     public function testSendAsyncWithInvalidUri()
     {
         $request = self::$messageFactory->createRequest(
             'GET',
             $this->getInvalidUri(),
-            $this->defaultHeaders
+            self::$defaultHeaders
         );
 
         $exception = null;
@@ -159,6 +164,8 @@ public function testSendAsyncWithInvalidUri()
      * @dataProvider requestWithOutcomeProvider
      * @group        integration
      */
+    #[Group('integration')]
+    #[DataProvider('requestWithOutcomeProvider')]
     public function testSendAsyncRequestWithOutcome($uriAndOutcome, $protocolVersion, array $headers, $body)
     {
         if ('1.0' === $protocolVersion) {
diff --git a/src/HttpBaseTest.php b/src/HttpBaseTest.php
index cbf7a4f..e735126 100644
--- a/src/HttpBaseTest.php
+++ b/src/HttpBaseTest.php
@@ -10,8 +10,6 @@
 
 abstract class HttpBaseTest extends TestCase
 {
-    use PhpUnitBackwardCompatibleTrait;
-
     /**
      * @var string
      */
@@ -36,7 +34,7 @@ abstract class HttpBaseTest extends TestCase
     /**
      * @var array
      */
-    protected $defaultHeaders = [
+    protected static $defaultHeaders = [
         'Connection' => 'close',
         'User-Agent' => 'PHP HTTP Adapter',
         'Content-Length' => '0',
@@ -61,13 +59,13 @@ public static function tearDownAfterClass(): void
         }
     }
 
-    public function requestProvider(): array
+    public static function requestProvider(): array
     {
         $sets = [
-            'methods' => $this->getMethods(),
-            'uris' => [$this->getUri()],
-            'headers' => $this->getHeaders(),
-            'body' => $this->getBodies(),
+            'methods' => self::getMethods(),
+            'uris' => [self::getUri()],
+            'headers' => self::getHeaders(),
+            'body' => self::getBodies(),
         ];
 
         $cartesianProduct = new CartesianProduct($sets);
@@ -84,13 +82,13 @@ public function requestProvider(): array
         });
     }
 
-    public function requestWithOutcomeProvider(): array
+    public static function requestWithOutcomeProvider(): array
     {
         $sets = [
-            'urisAndOutcomes' => $this->getUrisAndOutcomes(),
-            'protocolVersions' => $this->getProtocolVersions(),
-            'headers' => $this->getHeaders(),
-            'body' => $this->getBodies(),
+            'urisAndOutcomes' => self::getUrisAndOutcomes(),
+            'protocolVersions' => self::getProtocolVersions(),
+            'headers' => self::getHeaders(),
+            'body' => self::getBodies(),
         ];
 
         $cartesianProduct = new CartesianProduct($sets);
@@ -98,7 +96,7 @@ public function requestWithOutcomeProvider(): array
         return $cartesianProduct->compute();
     }
 
-    private function getMethods(): array
+    private static function getMethods(): array
     {
         return [
             'GET',
@@ -116,7 +114,7 @@ private function getMethods(): array
      *
      * @return string|null
      */
-    protected function getUri(array $query = [])
+    protected static function getUri(array $query = [])
     {
         return !empty($query)
             ? PHPUnitUtility::getUri().'?'.http_build_query($query, '', '&')
@@ -134,25 +132,25 @@ protected function getInvalidUri()
     /**
      * @return array
      */
-    private function getUrisAndOutcomes()
+    private static function getUrisAndOutcomes()
     {
         return [
             [
-                $this->getUri(['client_error' => true]),
+                self::getUri(['client_error' => true]),
                 [
                     'statusCode' => 400,
                     'reasonPhrase' => 'Bad Request',
                 ],
             ],
             [
-                $this->getUri(['server_error' => true]),
+                self::getUri(['server_error' => true]),
                 [
                     'statusCode' => 500,
                     'reasonPhrase' => 'Internal Server Error',
                 ],
             ],
             [
-                $this->getUri(['redirect' => true]),
+                self::getUri(['redirect' => true]),
                 [
                     'statusCode' => 302,
                     'reasonPhrase' => 'Found',
@@ -165,7 +163,7 @@ private function getUrisAndOutcomes()
     /**
      * @return array
      */
-    private function getProtocolVersions()
+    private static function getProtocolVersions()
     {
         return ['1.1', '1.0'];
     }
@@ -173,14 +171,14 @@ private function getProtocolVersions()
     /**
      * @return string[]
      */
-    private function getHeaders()
+    private static function getHeaders()
     {
-        $headers = $this->defaultHeaders;
+        $headers = self::$defaultHeaders;
         $headers['Accept-Charset'] = 'utf-8';
         $headers['Accept-Language'] = 'en';
 
         return [
-            $this->defaultHeaders,
+            self::$defaultHeaders,
             $headers,
         ];
     }
@@ -188,18 +186,18 @@ private function getHeaders()
     /**
      * @return array
      */
-    private function getBodies()
+    private static function getBodies()
     {
         return [
             null,
-            http_build_query($this->getData(), '', '&'),
+            http_build_query(self::getData(), '', '&'),
         ];
     }
 
     /**
      * @return array
      */
-    private function getData()
+    private static function getData()
     {
         return ['param1' => 'foo', 'param2' => ['bar', ['baz']]];
     }
@@ -223,7 +221,7 @@ protected function assertResponse(ResponseInterface $response, array $options =
         if (null === $options['body']) {
             $this->assertEmpty($response->getBody()->__toString());
         } else {
-            $this->assertStringContainsString($options['body'], $response->getBody()->__toString());
+            self::assertStringContainsString($options['body'], $response->getBody()->__toString());
         }
     }
 
diff --git a/src/HttpClientTest.php b/src/HttpClientTest.php
index aaaf7a4..884a319 100644
--- a/src/HttpClientTest.php
+++ b/src/HttpClientTest.php
@@ -2,6 +2,8 @@
 
 namespace Http\Client\Tests;
 
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\Group;
 use Psr\Http\Client\ClientInterface;
 use Psr\Http\Client\NetworkExceptionInterface;
 
@@ -37,6 +39,8 @@ abstract protected function createHttpAdapter(): ClientInterface;
      * @dataProvider requestProvider
      * @group        integration
      */
+    #[Group('integration')]
+    #[DataProvider('requestProvider')]
     public function testSendRequest($method, $uri, array $headers, $body)
     {
         if (null != $body) {
@@ -65,6 +69,8 @@ public function testSendRequest($method, $uri, array $headers, $body)
      * @dataProvider requestWithOutcomeProvider
      * @group        integration
      */
+    #[Group('integration')]
+    #[DataProvider('requestWithOutcomeProvider')]
     public function testSendRequestWithOutcome($uriAndOutcome, $protocolVersion, array $headers, $body)
     {
         if ('1.0' === $protocolVersion) {
@@ -95,12 +101,13 @@ public function testSendRequestWithOutcome($uriAndOutcome, $protocolVersion, arr
     /**
      * @group integration
      */
+    #[Group('integration')]
     public function testSendWithInvalidUri()
     {
         $request = self::$messageFactory->createRequest(
             'GET',
             $this->getInvalidUri(),
-            $this->defaultHeaders
+            self::$defaultHeaders
         );
 
         $this->expectException(NetworkExceptionInterface::class);
diff --git a/src/HttpFeatureTest.php b/src/HttpFeatureTest.php
index a8faf33..7823ffd 100644
--- a/src/HttpFeatureTest.php
+++ b/src/HttpFeatureTest.php
@@ -9,8 +9,6 @@
 
 abstract class HttpFeatureTest extends TestCase
 {
-    use PhpUnitBackwardCompatibleTrait;
-
     /**
      * @var MessageFactory
      */
diff --git a/src/PhpUnitBackwardCompatibleTrait.php b/src/PhpUnitBackwardCompatibleTrait.php
index 05f094d..89380a9 100644
--- a/src/PhpUnitBackwardCompatibleTrait.php
+++ b/src/PhpUnitBackwardCompatibleTrait.php
@@ -4,6 +4,9 @@
 
 use PHPUnit\Framework\TestCase;
 
+/**
+ * @deprecated this trait was to help using phpunit 7 and 8 which are obsolete. this trait will be removed in the next major version.
+ */
 trait PhpUnitBackwardCompatibleTrait
 {
     public static function assertStringContainsString(string $needle, string $haystack, string $message = ''): void