diff --git a/.eslintrc.json b/.eslintrc.json
index 1a49e0ab..6cd5dc3f 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -2,7 +2,8 @@
 	"root": true,
 	"extends": "wikimedia",
 	"env": {
-		"browser": true
+		"browser": true,
+		"commonjs": true
 	},
 	"globals": {
 		"mw": false,
diff --git a/extension.json b/extension.json
index a538ee45..9ba21c22 100644
--- a/extension.json
+++ b/extension.json
@@ -6,7 +6,7 @@
 	"license-name": "GPL-2.0-or-later",
 	"type": "parserhook",
 	"requires": {
-		"MediaWiki": ">= 1.29.0"
+		"MediaWiki": ">= 1.33.0"
 	},
 	"ConfigRegistry": {
 		"categorytree": "GlobalVarConfig::newInstance"
@@ -41,8 +41,16 @@
 	},
 	"ResourceModules": {
 		"ext.categoryTree": {
-			"scripts": "ext.categoryTree/ext.categoryTree.js",
-			"styles": "ext.categoryTree/ext.categoryTree.css",
+			"localBasePath": "modules/ext.categoryTree",
+			"remoteExtPath": "CategoryTree/modules/ext.categoryTree",
+			"styles": "ext.categoryTree.css",
+			"packageFiles": [
+				"ext.categoryTree.js",
+				{
+					"name": "data.json",
+					"callback": "CategoryTreeHooks::getDataForJs"
+				}
+			],
 			"targets": [
 				"desktop",
 				"mobile"
@@ -78,17 +86,10 @@
 		"remoteExtPath": "CategoryTree/modules"
 	},
 	"Hooks": {
-		"ArticleFromTitle": [
-			"CategoryTreeHooks::articleFromTitle"
-		],
-		"SpecialTrackingCategories::preprocess": [
-			"CategoryTreeHooks::onSpecialTrackingCategoriesPreprocess"
-		],
-		"SpecialTrackingCategories::generateCatLink": [
-			"CategoryTreeHooks::onSpecialTrackingCategoriesGenerateCatLink"
-		],
+		"ArticleFromTitle": "CategoryTreeHooks::articleFromTitle",
+		"SpecialTrackingCategories::preprocess": "CategoryTreeHooks::onSpecialTrackingCategoriesPreprocess",
+		"SpecialTrackingCategories::generateCatLink": "CategoryTreeHooks::onSpecialTrackingCategoriesGenerateCatLink",
 		"SkinBuildSidebar": "CategoryTreeHooks::onSkinBuildSidebar",
-		"MakeGlobalVariablesScript": "CategoryTreeHooks::getConfigVars",
 		"ParserFirstCallInit": "CategoryTreeHooks::setHooks",
 		"OutputPageMakeCategoryLinks": "CategoryTreeHooks::outputPageMakeCategoryLinks",
 		"BeforePageDisplay": "CategoryTreeHooks::addHeaders",
diff --git a/includes/CategoryTreeHooks.php b/includes/CategoryTreeHooks.php
index e6e1ed5d..9d777801 100644
--- a/includes/CategoryTreeHooks.php
+++ b/includes/CategoryTreeHooks.php
@@ -245,15 +245,20 @@ class CategoryTreeHooks {
 	}
 
 	/**
-	 * MakeGlobalVariablesScript hook
-	 * @param array &$vars
+	 * Get exported data for the "ext.categoryTree" ResourceLoader module.
+	 *
+	 * @internal For use in extension.json only.
+	 * @return array Data to be serialised as data.json
 	 */
-	public static function getConfigVars( array &$vars ) {
+	public static function getDataForJs() {
 		global $wgCategoryTreeCategoryPageOptions;
 
-		// Look this is pretty bad but Category tree is just whacky, it needs to be rewritten
+		// Look, this is pretty bad but CategoryTree is just whacky, it needs to be rewritten
 		$ct = new CategoryTree( $wgCategoryTreeCategoryPageOptions );
-		$vars['wgCategoryTreePageCategoryOptions'] = $ct->getOptionsAsJsStructure();
+
+		return [
+			'defaultCtOptions' => $ct->getOptionsAsJsStructure(),
+		];
 	}
 
 	/**
diff --git a/modules/ext.categoryTree/ext.categoryTree.js b/modules/ext.categoryTree/ext.categoryTree.js
index 91e0b69d..537c5804 100644
--- a/modules/ext.categoryTree/ext.categoryTree.js
+++ b/modules/ext.categoryTree/ext.categoryTree.js
@@ -24,7 +24,8 @@
  */
 
 ( function () {
-	var loadChildren;
+	var loadChildren,
+		data = require( './data.json' );
 
 	/**
 	 * Expands a given node (loading it's children if not loaded)
@@ -144,10 +145,7 @@
 		ctTitle = $link.attr( 'data-ct-title' );
 		ctMode = $linkParentCTTag.data( 'ct-mode' );
 		ctMode = typeof ctMode === 'number' ? ctMode : undefined;
-		ctOptions = $linkParentCTTag.attr( 'data-ct-options' );
-		if ( !ctOptions ) {
-			ctOptions = mw.config.get( 'wgCategoryTreePageCategoryOptions' );
-		}
+		ctOptions = $linkParentCTTag.attr( 'data-ct-options' ) || data.defaultCtOptions;
 
 		// Mode and options have defaults or fallbacks, title does not.
 		// Don't make a request if there is no title.