diff --git a/includes/Partials/PageTools.php b/includes/Partials/PageTools.php
index 929f44765..599a7167d 100644
--- a/includes/Partials/PageTools.php
+++ b/includes/Partials/PageTools.php
@@ -30,6 +30,9 @@
 use MediaWiki\MediaWikiServices;
 
 final class PageTools extends Partial {
+	/** @var null|array for caching purposes */
+	private $languages;
+
 	/**
 	 * Get page-related tools template data
 	 * TODO: Break this down and clean up when 1.39