diff --git a/packages/wxt/e2e/tests/encoding.test.ts b/packages/wxt/e2e/tests/encoding.test.ts
new file mode 100644
index 00000000..0364c9ff
--- /dev/null
+++ b/packages/wxt/e2e/tests/encoding.test.ts
@@ -0,0 +1,25 @@
+import { readFile } from 'node:fs/promises';
+import { describe, expect, it } from 'vitest';
+import { TestProject } from '../utils';
+
+describe('Encoding', () => {
+  it('should convert unicode characters to ascii escaped chars', async () => {
+    // See more details about this test, see:
+    // https://github.com/wxt-dev/wxt/issues/353#issuecomment-4093271292
+    const KNOWN_BAD_CHAR = '￿';
+    const ESCAPED_BAD_CHAR = '\\uFFFF';
+
+    const project = new TestProject();
+
+    // `project.addFile` writes the file as UTF8
+    project.addFile(
+      'entrypoints/example.ts',
+      `export default defineUnlistedScript(() => console.log('${KNOWN_BAD_CHAR}'))`,
+    );
+    await project.build();
+
+    const file = project.resolvePath('.output/chrome-mv3/example.js');
+    const asciiOutput = await readFile(file, 'ascii');
+    expect(asciiOutput).toContain(ESCAPED_BAD_CHAR);
+  });
+});
diff --git a/packages/wxt/src/core/builders/vite/index.ts b/packages/wxt/src/core/builders/vite/index.ts
index 7853191a..298bf4df 100644
--- a/packages/wxt/src/core/builders/vite/index.ts
+++ b/packages/wxt/src/core/builders/vite/index.ts
@@ -1,4 +1,10 @@
+import { Hookable } from 'hookable';
+import { mkdir, readdir, rename, rmdir, stat } from 'node:fs/promises';
+import { dirname, extname, join, relative } from 'node:path';
 import type * as vite from 'vite';
+import { ViteNodeRunner } from 'vite-node/client';
+import { ViteNodeServer } from 'vite-node/server';
+import { installSourcemapsSupport } from 'vite-node/source-map';
 import {
   BuildStepOutput,
   Entrypoint,
@@ -9,25 +15,19 @@ import {
   WxtDevServer,
   WxtHooks,
 } from '../../../types';
-import * as wxtPlugins from './plugins';
+import { normalizePath } from '../../utils';
+import { toArray } from '../../utils/arrays';
 import {
   getEntrypointBundlePath,
   isHtmlEntrypoint,
 } from '../../utils/entrypoints';
+import { createExtensionEnvironment } from '../../utils/environments';
+import { safeVarName } from '../../utils/strings';
 import {
   VirtualEntrypointType,
   VirtualModuleId,
 } from '../../utils/virtual-modules';
-import { Hookable } from 'hookable';
-import { toArray } from '../../utils/arrays';
-import { safeVarName } from '../../utils/strings';
-import { ViteNodeServer } from 'vite-node/server';
-import { ViteNodeRunner } from 'vite-node/client';
-import { installSourcemapsSupport } from 'vite-node/source-map';
-import { createExtensionEnvironment } from '../../utils/environments';
-import { dirname, extname, join, relative } from 'node:path';
-import { mkdir, readdir, rename, rmdir, stat } from 'node:fs/promises';
-import { normalizePath } from '../../utils';
+import * as wxtPlugins from './plugins';
 
 export async function createViteBuilder(
   wxtConfig: ResolvedConfig,
@@ -75,6 +75,10 @@ export async function createViteBuilder(
     // @ts-ignore: Untyped option:
     config.legacy.skipWebSocketTokenCheck = true;
 
+    // Solves https://github.com/wxt-dev/wxt/issues/353
+    config.esbuild ??= {};
+    if (config.esbuild) config.esbuild.charset = 'ascii';
+
     const server = getWxtDevServer?.();
 
     config.plugins ??= [];