diff --git a/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit.php b/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit.php
index 08be74fc72..7cfd6665d1 100644
--- a/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit.php
+++ b/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit.php
@@ -231,7 +231,7 @@ if (!file_exists("$PHPUNIT_DIR/$PHPUNIT_VERSION_DIR/phpunit") || $configurationH
     }
     $prevRoot = getenv('COMPOSER_ROOT_VERSION');
     putenv("COMPOSER_ROOT_VERSION=$PHPUNIT_VERSION.99");
-    $q = '\\' === \DIRECTORY_SEPARATOR ? '"' : '';
+    $q = '\\' === \DIRECTORY_SEPARATOR && \PHP_VERSION_ID < 80000 ? '"' : '';
     // --no-suggest is not in the list to keep compat with composer 1.0, which is shipped with Ubuntu 16.04LTS
     $exit = proc_close(proc_open("$q$COMPOSER install --no-dev --prefer-dist --no-progress $q", [], $p, getcwd()));
     putenv('COMPOSER_ROOT_VERSION'.(false !== $prevRoot ? '='.$prevRoot : ''));