diff --git a/packages/svelte/tests/runtime-legacy/shared.ts b/packages/svelte/tests/runtime-legacy/shared.ts
index 2c6a554727..17069a94ba 100644
--- a/packages/svelte/tests/runtime-legacy/shared.ts
+++ b/packages/svelte/tests/runtime-legacy/shared.ts
@@ -26,6 +26,20 @@ type Assert = typeof import('vitest').assert & {
 	): void;
 };
 
+// TODO remove this shim when we can
+// @ts-expect-error
+Promise.withResolvers = () => {
+	let resolve;
+	let reject;
+
+	const promise = new Promise((f, r) => {
+		resolve = f;
+		reject = r;
+	});
+
+	return { promise, resolve, reject };
+};
+
 export interface RuntimeTest<Props extends Record<string, any> = Record<string, any>>
 	extends BaseTest {
 	/** Use e.g. `mode: ['client']` to indicate that this test should never run in server/hydrate modes */
diff --git a/packages/svelte/tests/runtime-runes/samples/async-if/_config.js b/packages/svelte/tests/runtime-runes/samples/async-if/_config.js
index 991cebad3e..0bf9152dca 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-if/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/async-if/_config.js
@@ -6,7 +6,7 @@ import { test } from '../../test';
 let d;
 
 export default test({
-	html: `<p>pending</p>`,
+	html: `<button>reset</button><button>true</button><button>false</button><p>pending</p>`,
 
 	get props() {
 		d = deferred();
@@ -16,21 +16,31 @@ export default test({
 		};
 	},
 
-	async test({ assert, target, component }) {
-		d.resolve(true);
+	async test({ assert, target }) {
+		const [reset, t, f] = target.querySelectorAll('button');
+
+		flushSync(() => t.click());
 		await Promise.resolve();
 		await Promise.resolve();
 		await tick();
 		flushSync();
-		assert.htmlEqual(target.innerHTML, '<h1>yes</h1>');
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>reset</button><button>true</button><button>false</button><h1>yes</h1>'
+		);
 
-		d = deferred();
-		component.promise = d.promise;
+		flushSync(() => reset.click());
 		await tick();
-		assert.htmlEqual(target.innerHTML, '<h1>yes</h1>');
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>reset</button><button>true</button><button>false</button><h1>yes</h1>'
+		);
 
-		d.resolve(false);
+		flushSync(() => f.click());
 		await tick();
-		assert.htmlEqual(target.innerHTML, '<h1>no</h1>');
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>reset</button><button>true</button><button>false</button><h1>no</h1>'
+		);
 	}
 });
diff --git a/packages/svelte/tests/runtime-runes/samples/async-if/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-if/main.svelte
index baed33a76e..21a4cbef97 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-if/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/async-if/main.svelte
@@ -1,9 +1,13 @@
 <script>
-	let { promise } = $props();
+	let deferred = $state(Promise.withResolvers());
 </script>
 
+<button onclick={() => deferred = Promise.withResolvers()}>reset</button>
+<button onclick={() => deferred.resolve(true)}>true</button>
+<button onclick={() => deferred.resolve(false)}>false</button>
+
 <svelte:boundary>
-	{#if await promise}
+	{#if await deferred.promise}
 		<h1>yes</h1>
 	{:else}
 		<h1>no</h1>