diff --git a/app/assets/javascripts/discourse/app/models/bookmark.js b/app/assets/javascripts/discourse/app/models/bookmark.js
index ba5a34777d8..585fa7a868f 100644
--- a/app/assets/javascripts/discourse/app/models/bookmark.js
+++ b/app/assets/javascripts/discourse/app/models/bookmark.js
@@ -171,7 +171,6 @@ const Bookmark = RestModel.extend({
 Bookmark.reopenClass({
   create(args) {
     args = args || {};
-    args.siteSettings = args.siteSettings || Discourse.SiteSettings;
     args.currentUser = args.currentUser || Discourse.currentUser;
     return this._super(args);
   }
diff --git a/app/assets/javascripts/discourse/app/models/composer.js b/app/assets/javascripts/discourse/app/models/composer.js
index f4d302775ad..571cfe268c0 100644
--- a/app/assets/javascripts/discourse/app/models/composer.js
+++ b/app/assets/javascripts/discourse/app/models/composer.js
@@ -1211,7 +1211,6 @@ Composer.reopenClass({
     args = args || {};
     args.user = args.user || User.current();
     args.site = args.site || Site.current();
-    args.siteSettings = args.siteSettings || Discourse.SiteSettings;
     return this._super(args);
   },
 
diff --git a/app/assets/javascripts/discourse/app/models/post.js b/app/assets/javascripts/discourse/app/models/post.js
index 35b600aae2e..18bc421fea4 100644
--- a/app/assets/javascripts/discourse/app/models/post.js
+++ b/app/assets/javascripts/discourse/app/models/post.js
@@ -1,6 +1,6 @@
 import I18n from "I18n";
 import discourseComputed from "discourse-common/utils/decorators";
-import EmberObject, { computed, get } from "@ember/object";
+import EmberObject, { get } from "@ember/object";
 import { isEmpty } from "@ember/utils";
 import { equal, and, or, not } from "@ember/object/computed";
 import { ajax } from "discourse/lib/ajax";
@@ -18,18 +18,6 @@ import User from "discourse/models/user";
 import showModal from "discourse/lib/show-modal";
 
 const Post = RestModel.extend({
-  // TODO: Remove this once one instantiate all `Discourse.Post` models via the store.
-  siteSettings: computed({
-    get() {
-      return Discourse.SiteSettings;
-    },
-
-    // prevents model created from json to overridde this property
-    set() {
-      return Discourse.SiteSettings;
-    }
-  }),
-
   @discourseComputed("url")
   shareUrl(url) {
     const user = User.current();
diff --git a/test/javascripts/helpers/component-test.js b/test/javascripts/helpers/component-test.js
index 0330f6e91a1..5322a8113b6 100644
--- a/test/javascripts/helpers/component-test.js
+++ b/test/javascripts/helpers/component-test.js
@@ -4,6 +4,7 @@ import { autoLoadModules } from "discourse/initializers/auto-load-modules";
 import TopicTrackingState from "discourse/models/topic-tracking-state";
 import User from "discourse/models/user";
 import Site from "discourse/models/site";
+import { currentSettings } from "helpers/site-settings";
 
 export default function(name, opts) {
   opts = opts || {};
@@ -15,7 +16,7 @@ export default function(name, opts) {
   test(name, function(assert) {
     this.site = Site.current();
 
-    this.registry.register("site-settings:main", Discourse.SiteSettings, {
+    this.registry.register("site-settings:main", currentSettings(), {
       instantiate: false
     });
     this.registry.register("capabilities:main", EmberObject);
@@ -25,7 +26,7 @@ export default function(name, opts) {
     this.registry.injection("component", "capabilities", "capabilities:main");
     this.registry.injection("component", "site", "site:main");
 
-    this.siteSettings = Discourse.SiteSettings;
+    this.siteSettings = currentSettings();
 
     autoLoadModules(this.registry, this.registry);
 
diff --git a/test/javascripts/helpers/create-store.js b/test/javascripts/helpers/create-store.js
index 5385a48fd05..c4758165098 100644
--- a/test/javascripts/helpers/create-store.js
+++ b/test/javascripts/helpers/create-store.js
@@ -4,6 +4,7 @@ import KeyValueStore from "discourse/lib/key-value-store";
 import TopicListAdapter from "discourse/adapters/topic-list";
 import TopicTrackingState from "discourse/models/topic-tracking-state";
 import { buildResolver } from "discourse-common/resolver";
+import { currentSettings } from "helpers/site-settings";
 
 const CatAdapter = RestAdapter.extend({
   primaryKey: "cat_id"
@@ -40,7 +41,7 @@ export default function(customLookup = () => {}) {
           return this._tracker;
         }
         if (type === "site-settings:main") {
-          this._settings = this._settings || Discourse.SiteSettings;
+          this._settings = this._settings || currentSettings();
           return this._settings;
         }
         return customLookup(type);
diff --git a/test/javascripts/helpers/qunit-helpers.js b/test/javascripts/helpers/qunit-helpers.js
index dca1e4b4f47..aed99d6634d 100644
--- a/test/javascripts/helpers/qunit-helpers.js
+++ b/test/javascripts/helpers/qunit-helpers.js
@@ -25,6 +25,7 @@ import { resetCustomPostMessageCallbacks } from "discourse/controllers/topic";
 import { _clearSnapshots } from "select-kit/components/composer-actions";
 import User from "discourse/models/user";
 import { mapRoutes } from "discourse/mapping-router";
+import { currentSettings, mergeSettings } from "helpers/site-settings";
 
 export function currentUser() {
   return User.create(sessionFixtures["/session/current.json"].current_user);
@@ -107,7 +108,7 @@ export function controllerModule(name, args = {}) {
     setup() {
       this.registry.register("router:main", mapRoutes());
       let controller = this.subject();
-      controller.siteSettings = Discourse.SiteSettings;
+      controller.siteSettings = currentSettings();
       if (args.setupController) {
         args.setupController(controller);
       }
@@ -119,8 +120,7 @@ export function controllerModule(name, args = {}) {
 export function discourseModule(name, hooks) {
   QUnit.module(name, {
     beforeEach() {
-      // Give us an API to change site settings without `Discourse.SiteSettings` in tests
-      this.siteSettings = Discourse.SiteSettings;
+      this.siteSettings = currentSettings();
       if (hooks && hooks.beforeEach) {
         hooks.beforeEach.call(this);
       }
@@ -161,16 +161,12 @@ export function acceptance(name, options) {
       }
 
       if (options.settings) {
-        Discourse.SiteSettings = jQuery.extend(
-          true,
-          Discourse.SiteSettings,
-          options.settings
-        );
+        mergeSettings(options.settings);
       }
-      this.siteSettings = Discourse.SiteSettings;
+      this.siteSettings = currentSettings();
 
       if (options.site) {
-        resetSite(Discourse.SiteSettings, options.site);
+        resetSite(currentSettings(), options.site);
       }
 
       clearOutletCache();
@@ -186,7 +182,7 @@ export function acceptance(name, options) {
       flushMap();
       localStorage.clear();
       User.resetCurrent();
-      resetSite(Discourse.SiteSettings);
+      resetSite(currentSettings());
       resetExtraClasses();
       clearOutletCache();
       clearHTMLCache();
diff --git a/test/javascripts/helpers/site-settings.js b/test/javascripts/helpers/site-settings.js
index 4d1181dbaf9..477dbefcd0e 100644
--- a/test/javascripts/helpers/site-settings.js
+++ b/test/javascripts/helpers/site-settings.js
@@ -1,6 +1,4 @@
-// discourse-skip-module
-
-Discourse.SiteSettingsOriginal = {
+const ORIGINAL_SETTINGS = {
   title: "QUnit Discourse Tests",
   site_logo_url: "/assets/logo.png",
   site_logo_url: "/assets/logo.png",
@@ -103,8 +101,40 @@ Discourse.SiteSettingsOriginal = {
   secure_media: false
 };
 
-Discourse.SiteSettings = jQuery.extend(
-  true,
-  {},
-  Discourse.SiteSettingsOriginal
-);
+let siteSettings = Object.assign({}, ORIGINAL_SETTINGS);
+Discourse.SiteSettings = siteSettings;
+
+export function currentSettings() {
+  return siteSettings;
+}
+
+// In debug mode, Ember will decorate objects with setters that remind you to use
+// this.set() because they are bound (even if you use `unbound` or `readonly` in templates!).
+// Site settings are only ever changed in tests and these warnings are not wanted, so we'll
+// strip them when resetting our settings between tests.
+function setValue(k, v) {
+  let desc = Object.getOwnPropertyDescriptor(siteSettings, k);
+  if (desc && !desc.writable) {
+    Object.defineProperty(siteSettings, k, { writable: true });
+  }
+  siteSettings[k] = v;
+}
+
+export function mergeSettings(other) {
+  for (let p in other) {
+    if (other.hasOwnProperty(p)) {
+      setValue(p, other[p]);
+    }
+  }
+  return siteSettings;
+}
+
+export function resetSettings() {
+  for (let p in siteSettings) {
+    if (siteSettings.hasOwnProperty(p)) {
+      let v = ORIGINAL_SETTINGS[p];
+      typeof v !== "undefined" ? setValue(p, v) : delete siteSettings[p];
+    }
+  }
+  return siteSettings;
+}
diff --git a/test/javascripts/test_helper.js b/test/javascripts/test_helper.js
index f20b2251ed5..256ed45c8b4 100644
--- a/test/javascripts/test_helper.js
+++ b/test/javascripts/test_helper.js
@@ -42,6 +42,8 @@
 //
 //= require jquery.magnific-popup.min.js
 
+let resetSettings = require("helpers/site-settings").resetSettings;
+
 const buildResolver = require("discourse-common/resolver").buildResolver;
 window.setResolver(buildResolver("discourse").create({ namespace: Discourse }));
 
@@ -104,6 +106,7 @@ function resetSite(siteSettings, extras) {
 }
 
 QUnit.testStart(function(ctx) {
+  resetSettings();
   server = createPretender.default;
   createPretender.applyDefaultHandlers(server);
   server.handlers = [];
@@ -149,8 +152,7 @@ QUnit.testStart(function(ctx) {
     );
   }
 
-  // Allow our tests to change site settings and have them reset before the next test
-  Discourse.SiteSettings = dup(Discourse.SiteSettingsOriginal);
+  resetSettings();
 
   let getURL = require("discourse-common/lib/get-url");
   getURL.setupURL(null, "http://localhost:3000", "");