diff --git a/phpunit/wp-theme-json-test.php b/phpunit/wp-theme-json-test.php
index 0d92d33faf88de..96fd1ec82c5f19 100644
--- a/phpunit/wp-theme-json-test.php
+++ b/phpunit/wp-theme-json-test.php
@@ -6,6 +6,20 @@
  */
 
 class WP_Theme_Json_Test extends WP_UnitTestCase {
+	/**
+	 * @var string|null
+	 */
+	private $theme_root;
+
+	/**
+	 * @var array|null
+	 */
+	private $orig_theme_dir;
+
+	/**
+	 * @var array|null
+	 */
+	private $queries;
 
 	public function set_up() {
 		parent::set_up();