diff --git a/UPGRADING.md b/UPGRADING.md
index 2d1e6068..1c8cd1aa 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -1,5 +1,15 @@
 # Upgrading ember-cli-flash
 
+## Upgrading to v6
+
+### FlashObject is no longer an EmberObject
+
+Most apps will be unaffected by this – unless they call `getFlashObject` to access flash messages.
+
+Prior to v6 `FlashObject` extended [EmberObject](https://api.emberjs.com/ember/release/classes/emberobject/) and supported methods like `get`, `getProperties`, `set`, and `setProperties`.
+
+It's now a native class, and property access can be done using regular dot syntax, eg `flash.get('message')` should be replaced with `flash.message`.
+
 ## Upgrading to v5
 
 ### Test helpers
diff --git a/ember-cli-flash/declarations/flash/object.d.ts b/ember-cli-flash/declarations/flash/object.d.ts
index 2a79190e..94168ca3 100644
--- a/ember-cli-flash/declarations/flash/object.d.ts
+++ b/ember-cli-flash/declarations/flash/object.d.ts
@@ -1,8 +1,6 @@
 declare module 'ember-cli-flash/flash/object' {
-  import EmberObject from '@ember/object';
-  import Evented from '@ember/object/evented';
-
-  class FlashObject extends EmberObject.extend(Evented) {
+  export default class FlashObject {
+    message: string;
     exiting: boolean;
     exitTimer: number;
     isExitable: boolean;
@@ -14,5 +12,4 @@ declare module 'ember-cli-flash/flash/object' {
     timerTask(): void;
     exitTimerTask(): void;
   }
-  export default FlashObject;
 }
diff --git a/ember-cli-flash/src/flash/object.js b/ember-cli-flash/src/flash/object.js
index 8acbfe8f..86b16dc9 100644
--- a/ember-cli-flash/src/flash/object.js
+++ b/ember-cli-flash/src/flash/object.js
@@ -1,34 +1,42 @@
-import Evented from '@ember/object/evented';
-import EmberObject, { set } from '@ember/object';
 import { cancel, later } from '@ember/runloop';
-import { guidFor } from '../utils/computed';
 import { isTesting, macroCondition } from '@embroider/macros';
+import { tracked } from '@glimmer/tracking';
+import { guidFor } from '@ember/object/internals';
+import { destroy, isDestroyed, registerDestructor } from '@ember/destroyable';
 
 // Disable timeout by default when running tests
 const defaultDisableTimeout = macroCondition(isTesting()) ? true : false;
 
-// Note:
-// To avoid https://github.com/adopted-ember-addons/ember-cli-flash/issues/341 from happening, this class can't simply be called Object
-export default class FlashObject extends EmberObject.extend(Evented) {
+export default class FlashObject {
   exitTimer = null;
-  exiting = false;
+  @tracked exiting = false;
+  @tracked message = '';
   isExitable = true;
   initializedTime = null;
 
   // testHelperDisableTimeout – Set by `disableTimeout` and `enableTimeout` in test-support.js
 
-  get disableTimeout() {
+  get _disableTimeout() {
     return this.testHelperDisableTimeout ?? defaultDisableTimeout;
   }
 
-  @(guidFor('message').readOnly())
-  _guid;
+  get _guid() {
+    return guidFor(this.message?.toString());
+  }
+
+  constructor(messageOptions) {
+    for (const [key, value] of Object.entries(messageOptions)) {
+      this[key] = value;
+    }
 
-  // eslint-disable-next-line ember/classic-decorator-hooks
-  init() {
-    super.init(...arguments);
+    registerDestructor(this, () => {
+      this.onDestroy?.();
 
-    if (this.disableTimeout || this.sticky) {
+      this._cancelTimer();
+      this._cancelTimer('exitTaskInstance');
+    });
+
+    if (this._disableTimeout || this.sticky) {
       return;
     }
     this.timerTask();
@@ -50,25 +58,14 @@ export default class FlashObject extends EmberObject.extend(Evented) {
       return;
     }
     this.exitTimerTask();
-    this.trigger('didExitMessage');
+    this.onDidExitMessage?.();
   }
-
-  willDestroy() {
-    if (this.onDestroy) {
-      this.onDestroy();
-    }
-
-    this._cancelTimer();
-    this._cancelTimer('exitTaskInstance');
-    super.willDestroy(...arguments);
-  }
-
   preventExit() {
-    set(this, 'isExitable', false);
+    this.isExitable = false;
   }
 
   allowExit() {
-    set(this, 'isExitable', true);
+    this.isExitable = true;
     this._checkIfShouldExit();
   }
 
@@ -79,19 +76,19 @@ export default class FlashObject extends EmberObject.extend(Evented) {
     const timerTaskInstance = later(() => {
       this.exitMessage();
     }, this.timeout);
-    set(this, 'timerTaskInstance', timerTaskInstance);
+    this.timerTaskInstance = timerTaskInstance;
   }
 
   exitTimerTask() {
-    if (this.isDestroyed) {
+    if (isDestroyed(this)) {
       return;
     }
-    set(this, 'exiting', true);
+    this.exiting = true;
     if (this.extendedTimeout) {
       let exitTaskInstance = later(() => {
         this._teardown();
       }, this.extendedTimeout);
-      set(this, 'exitTaskInstance', exitTaskInstance);
+      this.exitTaskInstance = exitTaskInstance;
     } else {
       this._teardown();
     }
@@ -99,7 +96,7 @@ export default class FlashObject extends EmberObject.extend(Evented) {
 
   _setInitializedTime() {
     let currentTime = new Date().getTime();
-    set(this, 'initializedTime', currentTime);
+    this.initializedTime = currentTime;
 
     return this.initializedTime;
   }
@@ -128,7 +125,7 @@ export default class FlashObject extends EmberObject.extend(Evented) {
     if (queue) {
       queue.removeObject(this);
     }
-    this.destroy();
-    this.trigger('didDestroyMessage');
+    destroy(this);
+    this.onDidDestroyMessage?.();
   }
 }
diff --git a/ember-cli-flash/src/services/flash-messages.js b/ember-cli-flash/src/services/flash-messages.js
index 40115c3b..174364ec 100644
--- a/ember-cli-flash/src/services/flash-messages.js
+++ b/ember-cli-flash/src/services/flash-messages.js
@@ -11,6 +11,7 @@ import objectWithout from '../utils/object-without';
 import { getOwner } from '@ember/application';
 import flashMessageOptions from '../utils/flash-message-options';
 import getWithDefault from '../utils/get-with-default';
+import { associateDestroyableChild } from '@ember/destroyable';
 
 export default class FlashMessagesService extends Service {
   @(equal('queue.length', 0).readOnly())
@@ -103,7 +104,9 @@ export default class FlashMessagesService extends Service {
       set(flashMessageOptions, key, option);
     }
 
-    return FlashMessage.create(flashMessageOptions);
+    const message = new FlashMessage(flashMessageOptions);
+    associateDestroyableChild(this, message);
+    return message;
   }
 
   _getOptionOrDefault(key, value) {
diff --git a/ember-cli-flash/src/utils/computed.js b/ember-cli-flash/src/utils/computed.js
deleted file mode 100644
index 0754e6dd..00000000
--- a/ember-cli-flash/src/utils/computed.js
+++ /dev/null
@@ -1,17 +0,0 @@
-import { computed, get } from '@ember/object';
-import { guidFor as emberGuidFor } from '@ember/object/internals';
-import { isNone } from '@ember/utils';
-
-export function guidFor(dependentKey) {
-  return computed(dependentKey, {
-    get() {
-      const value = get(this, dependentKey);
-
-      // it's possible that a value has no toString as some objects don't implement the guid field
-      // this early return it to avoid errors being thrown when calling undefined.toString()
-      if (isNone(value)) return;
-
-      return emberGuidFor(value.toString());
-    },
-  });
-}
diff --git a/test-app/tests/integration/components/flash-message-test.js b/test-app/tests/integration/components/flash-message-test.js
index 6e5c8a8b..7bf7bd36 100644
--- a/test-app/tests/integration/components/flash-message-test.js
+++ b/test-app/tests/integration/components/flash-message-test.js
@@ -4,12 +4,14 @@ import {
   click,
   find,
   render,
+  rerender,
   settled,
   triggerEvent,
 } from '@ember/test-helpers';
 import hbs from 'htmlbars-inline-precompile';
 import FlashMessage from 'ember-cli-flash/flash/object';
 import { next, later } from '@ember/runloop';
+import { isDestroyed } from '@ember/destroyable';
 
 const timeoutDefault = 1000;
 const TIMEOUT = 50;
@@ -18,7 +20,8 @@ module('Integration | Component | flash message', function (hooks) {
   setupRenderingTest(hooks);
 
   test('it renders a flash message', async function (assert) {
-    this.set('flash', FlashMessage.create({ message: 'hi', sticky: true }));
+    const flash = new FlashMessage({ message: 'hi', sticky: true });
+    this.set('flash', flash);
 
     await render(hbs`
       <FlashMessage @flash={{this.flash}} as |component flash|>
@@ -26,7 +29,12 @@ module('Integration | Component | flash message', function (hooks) {
       </FlashMessage>
     `);
 
-    assert.dom('*').hasText('hi');
+    assert.dom('*').hasText('hi', 'initial message is displayed');
+
+    flash.message = 'hello';
+    await rerender();
+
+    assert.dom('*').hasText('hello', 'updated message is displayed');
   });
 
   test('it renders with the right props', async function (assert) {
@@ -34,7 +42,7 @@ module('Integration | Component | flash message', function (hooks) {
 
     this.set(
       'flash',
-      FlashMessage.create({
+      new FlashMessage({
         message: 'test',
         type: 'test',
         timeout: TIMEOUT,
@@ -68,7 +76,7 @@ module('Integration | Component | flash message', function (hooks) {
   });
 
   test('it does not error when quickly removed from the DOM', async function (assert) {
-    this.set('flash', FlashMessage.create({ message: 'hi', sticky: true }));
+    this.set('flash', new FlashMessage({ message: 'hi', sticky: true }));
     this.set('flag', true);
 
     await render(hbs`
@@ -82,7 +90,7 @@ module('Integration | Component | flash message', function (hooks) {
     this.set('flag', false);
 
     await settled();
-    assert.ok(this.flash.isDestroyed, 'Flash Object isDestroyed');
+    assert.ok(isDestroyed(this.flash), 'Flash Object isDestroyed');
   });
 
   test('flash message is removed after timeout', async function (assert) {
@@ -90,7 +98,7 @@ module('Integration | Component | flash message', function (hooks) {
 
     this.set(
       'flash',
-      FlashMessage.create({
+      new FlashMessage({
         message: 'hi',
         sticky: false,
         timeout: timeoutDefault,
@@ -108,7 +116,7 @@ module('Integration | Component | flash message', function (hooks) {
       () => {
         assert.dom('*').hasText('hi');
         assert.notOk(
-          this.flash.isDestroyed,
+          isDestroyed(this.flash),
           'Flash is not destroyed immediately'
         );
       },
@@ -117,13 +125,13 @@ module('Integration | Component | flash message', function (hooks) {
 
     await settled();
 
-    assert.ok(this.flash.isDestroyed, 'Flash Object is destroyed');
+    assert.ok(isDestroyed(this.flash), 'Flash Object is destroyed');
   });
 
   test('flash message is removed after timeout if mouse enters', async function (assert) {
     assert.expect(3);
 
-    let flashObject = FlashMessage.create({
+    let flashObject = new FlashMessage({
       message: 'hi',
       sticky: false,
       timeout: timeoutDefault,
@@ -145,7 +153,7 @@ module('Integration | Component | flash message', function (hooks) {
 
         next(this, () => {
           assert.notOk(
-            flashObject.isDestroyed,
+            isDestroyed(flashObject),
             'Flash Object is not destroyed'
           );
           triggerEvent('#testFlash', 'mouseleave');
@@ -156,7 +164,7 @@ module('Integration | Component | flash message', function (hooks) {
 
     await settled();
 
-    assert.ok(flashObject.isDestroyed, 'Flash Object is destroyed');
+    assert.ok(isDestroyed(flashObject), 'Flash Object is destroyed');
   });
 
   test('a custom component can use the close closure action', async function (assert) {
@@ -164,7 +172,7 @@ module('Integration | Component | flash message', function (hooks) {
 
     this.set(
       'flash',
-      FlashMessage.create({
+      new FlashMessage({
         message: 'flash message content',
         sticky: true,
         destroyOnClick: false,
@@ -178,21 +186,21 @@ module('Integration | Component | flash message', function (hooks) {
       </FlashMessage>
     `);
 
-    assert.notOk(this.flash.isDestroyed, 'flash has not been destroyed yet');
+    assert.notOk(isDestroyed(this.flash), 'flash has not been destroyed yet');
 
     await click('.alert');
-    assert.notOk(this.flash.isDestroyed, 'flash has not been destroyed yet');
+    assert.notOk(isDestroyed(this.flash), 'flash has not been destroyed yet');
 
     await click('.alert a');
     assert.ok(
-      this.flash.isDestroyed,
+      isDestroyed(this.flash),
       'flash is destroyed after clicking close'
     );
   });
 
   test('exiting class is applied for sticky messages', async function (assert) {
     assert.expect(2);
-    let flashObject = FlashMessage.create({
+    let flashObject = new FlashMessage({
       message: 'flash message content',
       sticky: true,
       extendedTimeout: 100,
@@ -208,12 +216,12 @@ module('Integration | Component | flash message', function (hooks) {
 
     await click('.alert');
     assert.dom('.alert').hasClass('exiting', 'exiting class is applied');
-    assert.ok(flashObject.isDestroyed, 'Flash Object is destroyed');
+    assert.ok(isDestroyed(flashObject), 'Flash Object is destroyed');
   });
 
   test('custom message type class name prefix is applied', async function (assert) {
     assert.expect(2);
-    let flashObject = FlashMessage.create({
+    let flashObject = new FlashMessage({
       message: 'flash message content',
       type: 'test',
       sticky: true,
diff --git a/test-app/tests/unit/flash/object-test.js b/test-app/tests/unit/flash/object-test.js
index 87d0ff60..b00d3212 100644
--- a/test-app/tests/unit/flash/object-test.js
+++ b/test-app/tests/unit/flash/object-test.js
@@ -3,6 +3,7 @@ import { isPresent } from '@ember/utils';
 import { module, test } from 'qunit';
 import FlashMessage from 'ember-cli-flash/flash/object';
 import { disableTimeout, enableTimeout } from 'ember-cli-flash/test-support';
+import { isDestroyed } from '@ember/destroyable';
 
 const testTimerDuration = 50;
 let flash = null;
@@ -10,7 +11,7 @@ let flash = null;
 module('FlashMessageObject disableTimeout', function (hooks) {
   hooks.beforeEach(function () {
     disableTimeout();
-    flash = FlashMessage.create({
+    flash = new FlashMessage({
       type: 'test',
       message: 'Cool story brah',
       timeout: testTimerDuration,
@@ -24,7 +25,7 @@ module('FlashMessageObject disableTimeout', function (hooks) {
   });
 
   test('it does not create a timer', function (assert) {
-    assert.notOk(flash.get('timerTaskInstance'), 'it does not create a timer');
+    assert.notOk(flash.timerTaskInstance, 'it does not create a timer');
   });
 });
 
@@ -32,7 +33,7 @@ module('FlashMessageObject enableTimeout', function (hooks) {
   hooks.beforeEach(function () {
     disableTimeout();
     enableTimeout();
-    flash = FlashMessage.create({
+    flash = new FlashMessage({
       type: 'test',
       message: 'Cool story brah',
       timeout: testTimerDuration,
@@ -45,16 +46,13 @@ module('FlashMessageObject enableTimeout', function (hooks) {
   });
 
   test('it sets a timer after init', function (assert) {
-    assert.ok(
-      isPresent(flash.get('timerTaskInstance')),
-      'it does create a timer'
-    );
+    assert.ok(isPresent(flash.timerTaskInstance), 'it does create a timer');
   });
 });
 
 module('FlashMessageObject', function (hooks) {
   hooks.beforeEach(function () {
-    flash = FlashMessage.create({
+    flash = new FlashMessage({
       type: 'test',
       message: 'Cool story brah',
       timeout: testTimerDuration,
@@ -70,7 +68,7 @@ module('FlashMessageObject', function (hooks) {
   });
 
   test('it sets a timer after init', function (assert) {
-    assert.ok(isPresent(flash.get('timerTaskInstance')));
+    assert.ok(isPresent(flash.timerTaskInstance));
   });
 
   test('it destroys the message after the timer has elapsed', function (assert) {
@@ -78,17 +76,17 @@ module('FlashMessageObject', function (hooks) {
     const done = assert.async();
     assert.expect(3);
 
-    flash.on('didDestroyMessage', () => {
+    flash.onDidDestroyMessage = () => {
       result = 'foo';
-    });
+    };
 
     later(() => {
-      assert.true(flash.isDestroyed, 'it sets `isDestroyed` to true');
+      assert.true(isDestroyed(flash), 'it sets `isDestroyed` to true');
       assert.notOk(flash.timer, 'it cancels the timer');
       assert.strictEqual(
         result,
         'foo',
-        'it emits the `didDestroyMessage` hook'
+        'it called the `onDidDestroyMessage` callback'
       );
       done();
     }, testTimerDuration * 2);
@@ -98,7 +96,7 @@ module('FlashMessageObject', function (hooks) {
     const done = assert.async();
     assert.expect(1);
 
-    const stickyFlash = FlashMessage.create({
+    const stickyFlash = new FlashMessage({
       type: 'test',
       message: 'Cool story brah',
       timeout: testTimerDuration,
@@ -107,7 +105,7 @@ module('FlashMessageObject', function (hooks) {
     });
 
     later(() => {
-      assert.false(stickyFlash.isDestroyed, 'it is not destroyed');
+      assert.false(isDestroyed(stickyFlash), 'it is not destroyed');
       done();
     }, testTimerDuration);
   });
@@ -119,22 +117,22 @@ module('FlashMessageObject', function (hooks) {
       flash.destroyMessage();
     });
 
-    assert.true(flash.get('isDestroyed'));
-    assert.notOk(flash.get('timer'));
+    assert.true(isDestroyed(flash));
+    assert.notOk(flash.timer);
   });
 
   test('it sets `exiting` to true after the timer has elapsed', function (assert) {
     assert.expect(2);
     const done = assert.async();
 
-    const exitFlash = FlashMessage.create({
+    const exitFlash = new FlashMessage({
       timeout: testTimerDuration,
       extendedTimeout: testTimerDuration,
     });
 
     later(() => {
-      assert.true(exitFlash.get('exiting'), 'it sets `exiting` to true');
-      assert.notOk(exitFlash.get('timer'), 'it cancels the `timer`');
+      assert.true(exitFlash.exiting, 'it sets `exiting` to true');
+      assert.notOk(exitFlash.timer, 'it cancels the `timer`');
       done();
     }, testTimerDuration * 2);
   });
@@ -142,7 +140,7 @@ module('FlashMessageObject', function (hooks) {
   test('it calls `onDestroy` when object is destroyed', function (assert) {
     assert.expect(1);
 
-    const callbackFlash = FlashMessage.create({
+    const callbackFlash = new FlashMessage({
       sticky: true,
       onDestroy() {
         assert.ok(true, 'onDestroy is called');
diff --git a/test-app/tests/unit/utils/computed-test.js b/test-app/tests/unit/utils/computed-test.js
deleted file mode 100644
index 8de5307d..00000000
--- a/test-app/tests/unit/utils/computed-test.js
+++ /dev/null
@@ -1,37 +0,0 @@
-/* eslint-disable ember/no-classic-classes */
-import { htmlSafe } from '@ember/template';
-import EmberObject from '@ember/object';
-import { guidFor } from 'ember-cli-flash/utils/computed';
-import { module, test } from 'qunit';
-
-module('Unit | Utility | computed', function () {
-  test('#guidFor generates a guid for a `dependentKey`', function (assert) {
-    const Flash = EmberObject.extend({
-      _guid: guidFor('message'),
-    });
-    const flash = Flash.create({
-      message: 'I like pie',
-    });
-    const result = flash._guid;
-    assert.ok(result, 'it generated a guid for `dependentKey`');
-  });
-
-  test('#guidFor generates the same guid for a message', function (assert) {
-    const Flash = EmberObject.extend({
-      _guid: guidFor('message'),
-    });
-    const flash = Flash.create({
-      message: htmlSafe('I like pie'),
-    });
-    const secondFlash = Flash.create({
-      message: htmlSafe('I like pie'),
-    });
-    const result = flash._guid;
-    const secondResult = secondFlash._guid;
-    assert.strictEqual(
-      result,
-      secondResult,
-      'it generated the same guid for messages that compute to the same string'
-    );
-  });
-});