diff --git a/.changeset/lovely-dancers-search.md b/.changeset/lovely-dancers-search.md
new file mode 100644
index 000000000000..a5a09c64ac45
--- /dev/null
+++ b/.changeset/lovely-dancers-search.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: determine local Svelte version more reliably
diff --git a/packages/kit/postinstall.js b/packages/kit/postinstall.js
index 8d6d9ed37b8e..5842304dd683 100644
--- a/packages/kit/postinstall.js
+++ b/packages/kit/postinstall.js
@@ -1,5 +1,4 @@
 import { load_config } from './src/core/config/index.js';
-import * as sync from './src/core/sync/sync.js';
 import glob from 'tiny-glob/sync.js';
 import fs from 'node:fs';
 
@@ -38,6 +37,9 @@ try {
 			const pkg = JSON.parse(fs.readFileSync('package.json', 'utf8'));
 			if (!pkg.dependencies?.['@sveltejs/kit'] && !pkg.devDependencies?.['@sveltejs/kit']) continue;
 
+			// defer import until after the chdir so that peer dependency resolves correctly
+			const sync = await import('./src/core/sync/sync.js');
+
 			try {
 				const config = await load_config();
 				sync.all(config, 'development');
diff --git a/packages/kit/src/core/sync/utils.js b/packages/kit/src/core/sync/utils.js
index 9e75fc074ce2..cf35fadb4940 100644
--- a/packages/kit/src/core/sync/utils.js
+++ b/packages/kit/src/core/sync/utils.js
@@ -1,7 +1,17 @@
 import fs from 'node:fs';
 import path from 'node:path';
-import { VERSION } from 'svelte/compiler';
 import { mkdirp } from '../../utils/filesystem.js';
+import { resolve_peer_dependency } from '../../utils/import.js';
+
+/** @type {string} */
+let VERSION;
+
+try {
+	({ VERSION } = await resolve_peer_dependency('svelte/compiler'));
+} catch {
+	// we can end up here from e.g. unit tests. this is the simplest fix
+	({ VERSION } = await import('svelte/compiler'));
+}
 
 /** @type {Map<string, string>} */
 const previous_contents = new Map();
diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index 402fa009bf64..2280025bcc62 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -1,7 +1,6 @@
 import fs from 'node:fs';
 import path from 'node:path';
 
-import * as imr from 'import-meta-resolve';
 import colors from 'kleur';
 
 import { copy, mkdirp, posixify, read, resolve_entry, rimraf } from '../../utils/filesystem.js';
@@ -34,7 +33,7 @@ import {
 	sveltekit_paths,
 	sveltekit_server
 } from './module_ids.js';
-import { pathToFileURL } from 'node:url';
+import { resolve_peer_dependency } from '../../utils/import.js';
 
 const cwd = process.cwd();
 
@@ -123,23 +122,6 @@ const warning_preprocessor = {
 	}
 };
 
-/**
- * Resolve a dependency relative to the current working directory,
- * rather than relative to this package
- * @param {string} dependency
- */
-async function resolve_peer_dependency(dependency) {
-	try {
-		// @ts-expect-error the types are wrong
-		const resolved = imr.resolve(dependency, pathToFileURL(process.cwd() + '/dummy.js'));
-		return import(resolved);
-	} catch {
-		throw new Error(
-			`Could not resolve peer dependency "${dependency}" relative to your project — please install it and try again.`
-		);
-	}
-}
-
 /**
  * Returns the SvelteKit Vite plugins.
  * @returns {Promise<import('vite').Plugin[]>}
diff --git a/packages/kit/src/utils/import.js b/packages/kit/src/utils/import.js
new file mode 100644
index 000000000000..ca49592e492b
--- /dev/null
+++ b/packages/kit/src/utils/import.js
@@ -0,0 +1,19 @@
+import * as imr from 'import-meta-resolve';
+import { pathToFileURL } from 'node:url';
+
+/**
+ * Resolve a dependency relative to the current working directory,
+ * rather than relative to this package
+ * @param {string} dependency
+ */
+export function resolve_peer_dependency(dependency) {
+	try {
+		// @ts-expect-error the types are wrong
+		const resolved = imr.resolve(dependency, pathToFileURL(process.cwd() + '/dummy.js'));
+		return import(resolved);
+	} catch {
+		throw new Error(
+			`Could not resolve peer dependency "${dependency}" relative to your project — please install it and try again.`
+		);
+	}
+}
diff --git a/scripts/sync-all.js b/scripts/sync-all.js
index a1d5b55c5e9a..d57b9fc2e4db 100644
--- a/scripts/sync-all.js
+++ b/scripts/sync-all.js
@@ -1,6 +1,5 @@
 import fs from 'node:fs';
 import path from 'node:path';
-import * as sync from '../packages/kit/src/core/sync/sync.js';
 import { load_config } from '../packages/kit/src/core/config/index.js';
 
 // This isn't strictly necessary, but it eliminates some annoying warnings in CI
@@ -13,10 +12,15 @@ for (const directories of [
 	for (const dir of fs.readdirSync(directories)) {
 		const cwd = path.join(directories, dir);
 
-		if (!fs.existsSync(path.join(cwd, 'svelte.config.js'))) {
+		if (!fs.existsSync('svelte.config.js')) {
 			continue;
 		}
 
+		process.chdir(cwd);
+
+		// we defer this import so that we don't try and resolve `svelte` from
+		// the root via `isSvelte5Plus`, which would blow up
+		const sync = await import('../packages/kit/src/core/sync/sync.js');
 		await sync.all(await load_config({ cwd }), 'development');
 	}
 }