diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 1620ca7..17058da 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -10,6 +10,14 @@ jobs:
       matrix:
         include:
           - php-version: '7.4'
+          - php-version: '8.0'
+          - php-version: '8.1'
+          - php-version: '8.2'
+          - php-version: '8.3'
+          - php-version: '8.4'
+            phpunit-flags: --display-deprecations --fail-on-deprecation
+          - php-version: '8.5'
+            phpunit-flags: --display-deprecations --fail-on-deprecation
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v5
@@ -17,6 +25,12 @@ jobs:
       - uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php-version }}
-          extensions: none
+          extensions: none, ctype, curl, dom, json, mbstring, tokenizer, xml, xmlwriter
+          ini-values: display_errors=On, display_startup_errors=On, error_reporting=-1, zend.assertions=1
 
-      - run: php --version
+      - run: composer update
+
+      - if: matrix.php-version != '7.4' && matrix.php-version != '8.0' # These run PHPUnit 9, which does not have the option
+        run: vendor/bin/phpunit --check-php-configuration
+
+      - run: vendor/bin/phpunit tests --no-configuration ${{ matrix.phpunit-flags }}
diff --git a/composer.json b/composer.json
index 32f29ef..29b005b 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
         "php": "^5.6 || ^7.0 || ^8.0"
     },
     "require-dev": {
-        "symfony/phpunit-bridge": "^5.1"
+        "phpunit/phpunit": "^9.6.24 || ^10.5.52 || ^11.5.33"
     },
     "config": {
         "optimize-autoloader": true,
diff --git a/src/AccessibleObject.php b/src/AccessibleObject.php
index 540e8a7..5bc6cd1 100644
--- a/src/AccessibleObject.php
+++ b/src/AccessibleObject.php
@@ -36,7 +36,7 @@ public function __call($name, array $arguments)
         }
 
         $method = $this->reflection->getMethod($name);
-        $method->setAccessible(true);
+        PHP_VERSION_ID < 80100 && $method->setAccessible(true);
 
         return $method->invokeArgs($this->object, $arguments);
     }
@@ -59,7 +59,7 @@ public function __get($name)
         }
 
         $property = $this->reflection->getProperty($name);
-        $property->setAccessible(true);
+        PHP_VERSION_ID < 80100 && $property->setAccessible(true);
 
         return $property->getValue($this->object);
     }
@@ -71,7 +71,7 @@ public function __set($name, $value)
         }
 
         $property = $this->reflection->getProperty($name);
-        $property->setAccessible(true);
+        PHP_VERSION_ID < 80100 && $property->setAccessible(true);
 
         $property->setValue($this->object, $value);
     }