diff --git a/package_manager/tests/modules/package_manager_bypass/src/PackageManagerBypassServiceProvider.php b/package_manager/tests/modules/package_manager_bypass/src/PackageManagerBypassServiceProvider.php
index 2e9ad4812bf178df171c1eed9ffe6d977e17a8fa..e9b95a50efe857846cd262b3ad23311005f9eb74 100644
--- a/package_manager/tests/modules/package_manager_bypass/src/PackageManagerBypassServiceProvider.php
+++ b/package_manager/tests/modules/package_manager_bypass/src/PackageManagerBypassServiceProvider.php
@@ -4,6 +4,7 @@ namespace Drupal\package_manager_bypass;
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\DependencyInjection\ServiceProviderBase;
+use Drupal\Core\Site\Settings;
 
 /**
  * Defines services to bypass Package Manager's core functionality.
@@ -20,6 +21,12 @@ class PackageManagerBypassServiceProvider extends ServiceProviderBase {
       ->setClass(Beginner::class);
     $container->getDefinition('package_manager.stager')
       ->setClass(Stager::class);
+
+    // Allow functional tests to disable specific validators as necessary.
+    // Kernel tests can override the ::register() method and modify the
+    // container directly.
+    $validators = Settings::get('package_manager_bypass_validators', []);
+    array_walk($validators, [$container, 'removeDefinition']);
   }
 
 }
diff --git a/package_manager/tests/src/Functional/ExcludedPathsTest.php b/package_manager/tests/src/Functional/ExcludedPathsTest.php
index 3fbe8808ab6063c5abccc41f9d649dcc2657b50e..97ed57a8a29ad10434f9849f0bc87cab338c2d99 100644
--- a/package_manager/tests/src/Functional/ExcludedPathsTest.php
+++ b/package_manager/tests/src/Functional/ExcludedPathsTest.php
@@ -22,7 +22,32 @@ class ExcludedPathsTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected static $modules = ['package_manager'];
+  protected static $modules = [
+    'package_manager',
+    'package_manager_bypass',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function prepareSettings() {
+    parent::prepareSettings();
+
+    // Disable the filesystem permissions validator, since we cannot guarantee
+    // that the current code base will be writable in all testing situations.
+    // We test this validator functionally in Automatic Updates' build tests,
+    // since those do give us control over the filesystem permissions.
+    // @see \Drupal\Tests\automatic_updates\Build\CoreUpdateTest::assertReadOnlyFileSystemError()
+    // @see \Drupal\Tests\package_manager\Kernel\WritableFileSystemValidatorTest
+    $this->writeSettings([
+      'settings' => [
+        'package_manager_bypass_validators' => (object) [
+          'value' => ['package_manager.validator.file_system'],
+          'required' => TRUE,
+        ],
+      ],
+    ]);
+  }
 
   /**
    * Tests that certain paths are excluded from staging areas.