diff --git a/app/assets/javascripts/admin/index.js b/app/assets/javascripts/admin/index.js
index 02238e5b63c..8889660fdb5 100644
--- a/app/assets/javascripts/admin/index.js
+++ b/app/assets/javascripts/admin/index.js
@@ -1,15 +1,26 @@
 "use strict";
 
 const calculateCacheKeyForTree = require("calculate-cache-key-for-tree");
+const path = require("path");
 
 module.exports = {
   name: require("./package").name,
-  treeForAddon(tree) {
-    let app = this._findHost();
-    app.options.adminTree = this._super.treeForAddon.call(this, tree);
+
+  // return an empty tree here as we do not want the addon modules to be
+  // included into vendor.js; instead, we will produce a separate bundle
+  // (admin.js) to be included via a script tag as needed
+  treeForAddon() {
     return;
   },
 
+  // custom method to produce the tree for admin.js
+  // called by ember-cli-build.js in discourse core
+  treeForAddonBundle() {
+    let addonTreePath = path.resolve(this.root, this.treePaths.addon);
+    let addonTree = this.treeGenerator(addonTreePath);
+    return this._super.treeForAddon.call(this, addonTree);
+  },
+
   cacheKeyForTree(tree) {
     return calculateCacheKeyForTree(tree, this);
   },
diff --git a/app/assets/javascripts/discourse/ember-cli-build.js b/app/assets/javascripts/discourse/ember-cli-build.js
index 76e64b6906e..bdc90104bdc 100644
--- a/app/assets/javascripts/discourse/ember-cli-build.js
+++ b/app/assets/javascripts/discourse/ember-cli-build.js
@@ -182,6 +182,10 @@ module.exports = function (defaults) {
     .findAddonByName("discourse-plugins")
     .generatePluginsTree();
 
+  const adminTree = app.project.findAddonByName("admin").treeForAddonBundle();
+
+  const wizardTree = app.project.findAddonByName("wizard").treeForAddonBundle();
+
   const terserPlugin = app.project.findAddonByName("ember-cli-terser");
   const applyTerser = (tree) => terserPlugin.postprocessTree("all", tree);
 
@@ -196,13 +200,13 @@ module.exports = function (defaults) {
     }),
     generateWorkboxTree(),
     applyTerser(
-      concat(mergeTrees([app.options.adminTree]), {
+      concat(adminTree, {
         inputFiles: ["**/*.js"],
         outputFile: `assets/admin.js`,
       })
     ),
     applyTerser(
-      concat(mergeTrees([app.options.wizardTree]), {
+      concat(wizardTree, {
         inputFiles: ["**/*.js"],
         outputFile: `assets/wizard.js`,
       })
diff --git a/app/assets/javascripts/wizard/index.js b/app/assets/javascripts/wizard/index.js
index f29529cc51a..afc67ba45b9 100644
--- a/app/assets/javascripts/wizard/index.js
+++ b/app/assets/javascripts/wizard/index.js
@@ -1,15 +1,26 @@
 "use strict";
 
 const calculateCacheKeyForTree = require("calculate-cache-key-for-tree");
+const path = require("path");
 
 module.exports = {
   name: require("./package").name,
-  treeForAddon(tree) {
-    let app = this._findHost();
-    app.options.wizardTree = this._super.treeForAddon.call(this, tree);
+
+  // return an empty tree here as we do not want the addon modules to be
+  // included into vendor.js; instead, we will produce a separate bundle
+  // (wizard.js) to be included via a script tag as needed
+  treeForAddon() {
     return;
   },
 
+  // custom method to produce the tree for wizard.js
+  // called by ember-cli-build.js in discourse core
+  treeForAddonBundle() {
+    let addonTreePath = path.resolve(this.root, this.treePaths.addon);
+    let addonTree = this.treeGenerator(addonTreePath);
+    return this._super.treeForAddon.call(this, addonTree);
+  },
+
   cacheKeyForTree(tree) {
     return calculateCacheKeyForTree(tree, this);
   },