diff --git a/phpBB/phpbb/attachment/upload.php b/phpBB/phpbb/attachment/upload.php
index ca83f9dabf..7cd94d0858 100644
--- a/phpBB/phpbb/attachment/upload.php
+++ b/phpBB/phpbb/attachment/upload.php
@@ -296,8 +296,10 @@ class upload
 	 */
 	protected function check_disk_space()
 	{
-		if ($free_space = @disk_free_space($this->phpbb_root_path . $this->config['upload_path']))
+		if (function_exists('disk_free_space'))
 		{
+			$free_space = @disk_free_space($this->phpbb_root_path);
+
 			if ($free_space <= $this->file->get('filesize'))
 			{
 				if ($this->auth->acl_get('a_'))
diff --git a/tests/attachment/upload_test.php b/tests/attachment/upload_test.php
index 9a30a20b23..c26efd5094 100644
--- a/tests/attachment/upload_test.php
+++ b/tests/attachment/upload_test.php
@@ -79,6 +79,7 @@ class phpbb_attachment_upload_test extends \phpbb_database_test_case
 			'img_create_thumbnail'	=> true,
 		));
 		$config = $this->config;
+		$this->phpbb_root_path = $phpbb_root_path;
 		$this->db = $this->new_dbal();
 		$this->cache = new \phpbb\cache\service(new \phpbb\cache\driver\dummy(), $this->config, $this->db, $phpbb_root_path, $phpEx);
 		$this->request = $this->createMock('\phpbb\request\request');