diff --git a/src/Symfony/Bridge/PhpUnit/Blacklist.php b/src/Symfony/Bridge/PhpUnit/Blacklist.php
new file mode 100644
index 0000000000..09ff256dec
--- /dev/null
+++ b/src/Symfony/Bridge/PhpUnit/Blacklist.php
@@ -0,0 +1,41 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bridge\PhpUnit;
+
+/**
+ * Utility class replacing PHPUnit's implementation of the same class.
+ *
+ * All files are blacklisted so that process-isolated tests don't start with broken
+ * "require_once" statements. Composer is the only supported way to load code there.
+ */
+class Blacklist
+{
+    public static $blacklistedClassNames = array();
+
+    public function getBlacklistedDirectories()
+    {
+        $root = dirname(__DIR__);
+        while ($root !== $parent = dirname($root)) {
+            $root = $parent;
+        }
+
+        return array($root);
+    }
+
+    public function isBlacklisted($file)
+    {
+        return true;
+    }
+}
+
+class_alias('Symfony\Bridge\PhpUnit\Blacklist', 'PHPUnit\Util\Blacklist');
+class_alias('Symfony\Bridge\PhpUnit\Blacklist', 'PHPUnit_Util_Blacklist');
diff --git a/src/Symfony/Bridge/PhpUnit/Legacy/SymfonyTestsListenerTrait.php b/src/Symfony/Bridge/PhpUnit/Legacy/SymfonyTestsListenerTrait.php
index b114c69c51..498919c099 100644
--- a/src/Symfony/Bridge/PhpUnit/Legacy/SymfonyTestsListenerTrait.php
+++ b/src/Symfony/Bridge/PhpUnit/Legacy/SymfonyTestsListenerTrait.php
@@ -15,7 +15,6 @@ use Doctrine\Common\Annotations\AnnotationRegistry;
 use PHPUnit\Framework\AssertionFailedError;
 use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\TestSuite;
-use PHPUnit\Util\Blacklist;
 use Symfony\Bridge\PhpUnit\ClockMock;
 use Symfony\Bridge\PhpUnit\DnsMock;
 
@@ -46,17 +45,6 @@ class SymfonyTestsListenerTrait
      */
     public function __construct(array $mockedNamespaces = array())
     {
-        if (class_exists('PHPUnit_Util_Blacklist')) {
-            \PHPUnit_Util_Blacklist::$blacklistedClassNames['\Symfony\Bridge\PhpUnit\DeprecationErrorHandler'] = 1;
-            \PHPUnit_Util_Blacklist::$blacklistedClassNames['\Symfony\Bridge\PhpUnit\SymfonyTestsListener'] = 1;
-            \PHPUnit_Util_Blacklist::$blacklistedClassNames['\Symfony\Bridge\PhpUnit\Legacy\SymfonyTestsListener'] = 1;
-            \PHPUnit_Util_Blacklist::$blacklistedClassNames['\Symfony\Bridge\PhpUnit\Legacy\SymfonyTestsListenerTrait'] = 1;
-        } else {
-            Blacklist::$blacklistedClassNames['\Symfony\Bridge\PhpUnit\DeprecationErrorHandler'] = 1;
-            Blacklist::$blacklistedClassNames['\Symfony\Bridge\PhpUnit\SymfonyTestsListener'] = 1;
-            Blacklist::$blacklistedClassNames['\Symfony\Bridge\PhpUnit\Legacy\SymfonyTestsListenerTrait'] = 1;
-        }
-
         $warn = false;
         foreach ($mockedNamespaces as $type => $namespaces) {
             if (!is_array($namespaces)) {
@@ -103,7 +91,7 @@ class SymfonyTestsListenerTrait
 
     public function startTestSuite($suite)
     {
-        if (class_exists('PHPUnit_Util_Blacklist', false)) {
+        if (class_exists('PHPUnit_Util_Test', false)) {
             $Test = 'PHPUnit_Util_Test';
         } else {
             $Test = 'PHPUnit\Util\Test';
@@ -190,7 +178,7 @@ class SymfonyTestsListenerTrait
                 putenv('SYMFONY_DEPRECATIONS_SERIALIZE='.$this->runsInSeparateProcess);
             }
 
-            if (class_exists('PHPUnit_Util_Blacklist', false)) {
+            if (class_exists('PHPUnit_Util_Test', false)) {
                 $Test = 'PHPUnit_Util_Test';
                 $AssertionFailedError = 'PHPUnit_Framework_AssertionFailedError';
             } else {
@@ -236,7 +224,7 @@ class SymfonyTestsListenerTrait
 
     public function endTest($test, $time)
     {
-        if (class_exists('PHPUnit_Util_Blacklist', false)) {
+        if (class_exists('PHPUnit_Util_Test', false)) {
             $Test = 'PHPUnit_Util_Test';
             $BaseTestRunner = 'PHPUnit_Runner_BaseTestRunner';
             $Warning = 'PHPUnit_Framework_Warning';
diff --git a/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit b/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit
index ac358dd4be..728ab1913d 100755
--- a/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit
+++ b/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit
@@ -82,17 +82,6 @@ if (!file_exists("$PHPUNIT_DIR/phpunit-$PHPUNIT_VERSION/phpunit") || md5_file(__
 define('PHPUNIT_COMPOSER_INSTALL', __DIR__.'/vendor/autoload.php');
 require PHPUNIT_COMPOSER_INSTALL;
 
-if (!class_exists('SymfonyBlacklistPhpunit', false)) {
-    class SymfonyBlacklistPhpunit {}
-}
-if (class_exists('PHPUnit_Util_Blacklist')) {
-    PHPUnit_Util_Blacklist::$blacklistedClassNames['SymfonyBlacklistPhpunit'] = 1;
-    PHPUnit_Util_Blacklist::$blacklistedClassNames['SymfonyBlacklistSimplePhpunit'] = 1;
-} else {
-    PHPUnit\Util\Blacklist::$blacklistedClassNames['SymfonyBlacklistPhpunit'] = 1;
-    PHPUnit\Util\Blacklist::$blacklistedClassNames['SymfonyBlacklistSimplePhpunit'] = 1;
-}
-
 Symfony\Bridge\PhpUnit\TextUI\Command::main();
 
 EOPHP
@@ -211,9 +200,6 @@ if ($components) {
         }
     }
 } elseif (!isset($argv[1]) || 'install' !== $argv[1] || file_exists('install')) {
-    if (!class_exists('SymfonyBlacklistSimplePhpunit', false)) {
-        class SymfonyBlacklistSimplePhpunit {}
-    }
     array_splice($argv, 1, 0, array('--colors=always'));
     $_SERVER['argv'] = $argv;
     $_SERVER['argc'] = ++$argc;
diff --git a/src/Symfony/Bridge/PhpUnit/bootstrap.php b/src/Symfony/Bridge/PhpUnit/bootstrap.php
index a265a129e6..1197ab050b 100644
--- a/src/Symfony/Bridge/PhpUnit/bootstrap.php
+++ b/src/Symfony/Bridge/PhpUnit/bootstrap.php
@@ -12,6 +12,9 @@
 use Doctrine\Common\Annotations\AnnotationRegistry;
 use Symfony\Bridge\PhpUnit\DeprecationErrorHandler;
 
+// Replace the native phpunit Blacklist, it's a broken artifact from the past
+require_once __DIR__.'/Blacklist.php';
+
 // Detect if we need to serialize deprecations to a file.
 if ($file = getenv('SYMFONY_DEPRECATIONS_SERIALIZE')) {
     DeprecationErrorHandler::collectDeprecations($file);