diff --git a/phpBB/config/services.yml b/phpBB/config/services.yml
index 5febe76c49..fb3e7aa964 100644
--- a/phpBB/config/services.yml
+++ b/phpBB/config/services.yml
@@ -131,6 +131,7 @@ services:
             - @dbal.conn
             - @config
             - @migrator
+            - @filesystem
             - %tables.ext%
             - %core.root_path%
             - .%core.php_ext%
diff --git a/phpBB/includes/extension/manager.php b/phpBB/includes/extension/manager.php
index 44a30c6280..de9a3937c3 100644
--- a/phpBB/includes/extension/manager.php
+++ b/phpBB/includes/extension/manager.php
@@ -44,13 +44,14 @@ class phpbb_extension_manager
 	* @param phpbb_db_driver $db A database connection
 	* @param phpbb_config $config phpbb_config
 	* @param phpbb_db_migrator $migrator
+	* @param phpbb_filesystem $filesystem
 	* @param string $extension_table The name of the table holding extensions
 	* @param string $phpbb_root_path Path to the phpbb includes directory.
 	* @param string $php_ext php file extension
 	* @param phpbb_cache_driver_interface $cache A cache instance or null
 	* @param string $cache_name The name of the cache variable, defaults to _ext
 	*/
-	public function __construct(ContainerInterface $container, phpbb_db_driver $db, phpbb_config $config, phpbb_db_migrator $migrator, $extension_table, $phpbb_root_path, $php_ext = '.php', phpbb_cache_driver_interface $cache = null, $cache_name = '_ext')
+	public function __construct(ContainerInterface $container, phpbb_db_driver $db, phpbb_config $config, phpbb_db_migrator $migrator, phpbb_filesystem $filesystem, $extension_table, $phpbb_root_path, $php_ext = '.php', phpbb_cache_driver_interface $cache = null, $cache_name = '_ext')
 	{
 		$this->container = $container;
 		$this->phpbb_root_path = $phpbb_root_path;
@@ -58,6 +59,7 @@ class phpbb_extension_manager
 		$this->config = $config;
 		$this->migrator = $migrator;
 		$this->cache = $cache;
+		$this->filesystem = $filesystem;
 		$this->php_ext = $php_ext;
 		$this->extension_table = $extension_table;
 		$this->cache_name = $cache_name;
@@ -510,7 +512,7 @@ class phpbb_extension_manager
 	*/
 	public function get_finder()
 	{
-		return new phpbb_extension_finder($this, $this->phpbb_root_path, $this->cache, $this->php_ext, $this->cache_name . '_finder');
+		return new phpbb_extension_finder($this, $this->filesystem, $this->phpbb_root_path, $this->cache, $this->php_ext, $this->cache_name . '_finder');
 	}
 
 	/**
diff --git a/tests/dbal/migrator_test.php b/tests/dbal/migrator_test.php
index 89669b85ec..745d260b38 100644
--- a/tests/dbal/migrator_test.php
+++ b/tests/dbal/migrator_test.php
@@ -60,6 +60,7 @@ class phpbb_dbal_migrator_test extends phpbb_database_test_case
 			$this->db,
 			$this->config,
 			$this->migrator,
+			new phpbb_filesystem(),
 			'phpbb_ext',
 			dirname(__FILE__) . '/../../phpBB/',
 			'.php',
diff --git a/tests/extension/finder_test.php b/tests/extension/finder_test.php
index 3781591b19..73c07ef79a 100644
--- a/tests/extension/finder_test.php
+++ b/tests/extension/finder_test.php
@@ -164,7 +164,7 @@ class phpbb_extension_finder_test extends phpbb_test_case
 	public function test_get_classes_create_cache()
 	{
 		$cache = new phpbb_mock_cache;
-		$finder = new phpbb_extension_finder($this->extension_manager, dirname(__FILE__) . '/', $cache, '.php', '_custom_cache_name');
+		$finder = new phpbb_extension_finder($this->extension_manager, new phpbb_filesystem(), dirname(__FILE__) . '/', $cache, '.php', '_custom_cache_name');
 		$files = $finder->suffix('_class.php')->get_files();
 
 		$expected_files = array(
@@ -204,6 +204,7 @@ class phpbb_extension_finder_test extends phpbb_test_case
 
 		$finder = new phpbb_extension_finder(
 			$this->extension_manager,
+			new phpbb_filesystem(),
 			dirname(__FILE__) . '/',
 			new phpbb_mock_cache(array(
 				'_ext_finder' => array(
diff --git a/tests/extension/manager_test.php b/tests/extension/manager_test.php
index 1f311116f4..d6bcb97586 100644
--- a/tests/extension/manager_test.php
+++ b/tests/extension/manager_test.php
@@ -112,6 +112,7 @@ class phpbb_extension_manager_test extends phpbb_database_test_case
 			$db,
 			$config,
 			$migrator,
+			new phpbb_filesystem(),
 			'phpbb_ext',
 			dirname(__FILE__) . '/',
 			'.' . $php_ext,
diff --git a/tests/extension/metadata_manager_test.php b/tests/extension/metadata_manager_test.php
index 081a32e277..df7817b479 100644
--- a/tests/extension/metadata_manager_test.php
+++ b/tests/extension/metadata_manager_test.php
@@ -64,6 +64,7 @@ class metadata_manager_test extends phpbb_database_test_case
 			$this->db,
 			$this->config,
 			$this->migrator,
+			new phpbb_filesystem(),
 			'phpbb_ext',
 			$this->phpbb_root_path,
 			$this->phpEx,
diff --git a/tests/mock/extension_manager.php b/tests/mock/extension_manager.php
index fdda4cbadc..954f2bf1c4 100644
--- a/tests/mock/extension_manager.php
+++ b/tests/mock/extension_manager.php
@@ -14,5 +14,6 @@ class phpbb_mock_extension_manager extends phpbb_extension_manager
 		$this->phpbb_root_path = $phpbb_root_path;
 		$this->php_ext = '.php';
 		$this->extensions = $extensions;
+		$this->filesystem = new phpbb_filesystem();
 	}
 }
diff --git a/tests/test_framework/phpbb_functional_test_case.php b/tests/test_framework/phpbb_functional_test_case.php
index 887dfea3b5..891fe237b3 100644
--- a/tests/test_framework/phpbb_functional_test_case.php
+++ b/tests/test_framework/phpbb_functional_test_case.php
@@ -153,6 +153,7 @@ class phpbb_functional_test_case extends phpbb_test_case
 			$db,
 			$config,
 			$migrator,
+			new phpbb_filesystem(),
 			self::$config['table_prefix'] . 'ext',
 			dirname(__FILE__) . '/',
 			'.' . $php_ext,