diff --git a/.changeset/slow-cats-argue.md b/.changeset/slow-cats-argue.md
new file mode 100644
index 000000000000..a3ad7ca6885d
--- /dev/null
+++ b/.changeset/slow-cats-argue.md
@@ -0,0 +1,7 @@
+---
+"@astrojs/sitemap": patch
+---
+
+Revert https://github.com/withastro/astro/pull/9846 
+
+The feature to customize the file name of the sitemap was reverted due to some internal issues with one of the dependencies. With an non-deterministic behaviour, the sitemap file was sometime emitted with incorrect syntax. 
diff --git a/packages/integrations/sitemap/src/index.ts b/packages/integrations/sitemap/src/index.ts
index 5d2a271d2cb9..11f19f5dea6e 100644
--- a/packages/integrations/sitemap/src/index.ts
+++ b/packages/integrations/sitemap/src/index.ts
@@ -1,14 +1,12 @@
 import type { AstroConfig, AstroIntegration } from 'astro';
-import path, { resolve } from 'node:path';
+import path from 'node:path';
 import { fileURLToPath } from 'node:url';
 import type { EnumChangefreq, LinkItem as LinkItemBase, SitemapItemLoose } from 'sitemap';
-import { SitemapAndIndexStream, SitemapStream, streamToPromise } from 'sitemap';
+import { simpleSitemapAndIndex } from 'sitemap';
 import { ZodError } from 'zod';
 
 import { generateSitemap } from './generate-sitemap.js';
 import { validateOptions } from './validate-options.js';
-import { createWriteStream } from 'node:fs';
-import { Readable } from 'node:stream';
 
 export { EnumChangefreq as ChangeFreqEnum } from 'sitemap';
 export type ChangeFreq = `${EnumChangefreq}`;
@@ -35,8 +33,6 @@ export type SitemapOptions =
 			lastmod?: Date;
 			priority?: number;
 
-			prefix?: string;
-
 			// called for each sitemap item just before to save them on disk, sync or async
 			serialize?(item: SitemapItem): SitemapItem | Promise<SitemapItem | undefined> | undefined;
 	  }
@@ -48,6 +44,7 @@ function formatConfigErrorMessage(err: ZodError) {
 }
 
 const PKG_NAME = '@astrojs/sitemap';
+const OUTFILE = 'sitemap-index.xml';
 const STATUS_CODE_PAGES = new Set(['404', '500']);
 
 function isStatusCodePage(pathname: string): boolean {
@@ -80,8 +77,7 @@ const createPlugin = (options?: SitemapOptions): AstroIntegration => {
 
 					const opts = validateOptions(config.site, options);
 
-					const { filter, customPages, serialize, entryLimit, prefix = 'sitemap-' } = opts;
-					const OUTFILE = `${prefix}index.xml`;
+					const { filter, customPages, serialize, entryLimit } = opts;
 
 					let finalSiteUrl: URL;
 					if (config.site) {
@@ -171,22 +167,13 @@ const createPlugin = (options?: SitemapOptions): AstroIntegration => {
 						}
 					}
 					const destDir = fileURLToPath(dir);
-
-					const sms = new SitemapAndIndexStream({
+					await simpleSitemapAndIndex({
+						hostname: finalSiteUrl.href,
+						destinationDir: destDir,
+						sourceData: urlData,
 						limit: entryLimit,
-						getSitemapStream: (i) => {
-							const sitemapStream = new SitemapStream({ hostname: finalSiteUrl.href });
-							const fileName = `${prefix}${i}.xml`;
-
-							const ws = sitemapStream.pipe(createWriteStream(resolve(destDir + fileName)));
-
-							return [new URL(fileName, finalSiteUrl.href).toString(), sitemapStream, ws];
-						},
+						gzip: false,
 					});
-
-					sms.pipe(createWriteStream(resolve(destDir + OUTFILE)));
-					await streamToPromise(Readable.from(urlData).pipe(sms));
-					sms.end();
 					logger.info(`\`${OUTFILE}\` created at \`${path.relative(process.cwd(), destDir)}\``);
 				} catch (err) {
 					if (err instanceof ZodError) {
diff --git a/packages/integrations/sitemap/src/schema.ts b/packages/integrations/sitemap/src/schema.ts
index da629fc0c690..a7682e881a05 100644
--- a/packages/integrations/sitemap/src/schema.ts
+++ b/packages/integrations/sitemap/src/schema.ts
@@ -34,13 +34,6 @@ export const SitemapOptionsSchema = z
 		changefreq: z.nativeEnum(ChangeFreq).optional(),
 		lastmod: z.date().optional(),
 		priority: z.number().min(0).max(1).optional(),
-
-		prefix: z
-			.string()
-			.regex(/^[a-zA-Z\-_]+$/gm, {
-				message: 'Only English alphabet symbols, hyphen and underscore allowed',
-			})
-			.optional(),
 	})
 	.strict()
 	.default(SITEMAP_CONFIG_DEFAULTS);
diff --git a/packages/integrations/sitemap/test/prefix.test.js b/packages/integrations/sitemap/test/prefix.test.js
deleted file mode 100644
index 16ec44e9f3c4..000000000000
--- a/packages/integrations/sitemap/test/prefix.test.js
+++ /dev/null
@@ -1,72 +0,0 @@
-import assert from 'node:assert/strict';
-import { before, describe, it } from 'node:test';
-import { sitemap } from './fixtures/static/deps.mjs';
-import { loadFixture, readXML } from './test-utils.js';
-
-describe('Prefix support', () => {
-	/** @type {import('./test-utils.js').Fixture} */
-	let fixture;
-	const prefix = 'test-';
-
-	describe('Static', () => {
-		before(async () => {
-			fixture = await loadFixture({
-				root: './fixtures/static/',
-				integrations: [
-					sitemap(),
-					sitemap({
-						prefix,
-					}),
-				],
-			});
-			await fixture.build();
-		});
-
-		it('Content is same', async () => {
-			const data = await readXML(fixture.readFile('/sitemap-0.xml'));
-			const prefixData = await readXML(fixture.readFile(`/${prefix}0.xml`));
-			assert.deepEqual(prefixData, data);
-		});
-
-		it('Index file load correct sitemap', async () => {
-			const data = await readXML(fixture.readFile('/sitemap-index.xml'));
-			const sitemapUrl = data.sitemapindex.sitemap[0].loc[0];
-			assert.strictEqual(sitemapUrl, 'http://example.com/sitemap-0.xml');
-
-			const prefixData = await readXML(fixture.readFile(`/${prefix}index.xml`));
-			const prefixSitemapUrl = prefixData.sitemapindex.sitemap[0].loc[0];
-			assert.strictEqual(prefixSitemapUrl, `http://example.com/${prefix}0.xml`);
-		});
-	});
-
-	describe('SSR', () => {
-		before(async () => {
-			fixture = await loadFixture({
-				root: './fixtures/ssr/',
-				integrations: [
-					sitemap(),
-					sitemap({
-						prefix,
-					}),
-				],
-			});
-			await fixture.build();
-		});
-
-		it('Content is same', async () => {
-			const data = await readXML(fixture.readFile('/client/sitemap-0.xml'));
-			const prefixData = await readXML(fixture.readFile(`/client/${prefix}0.xml`));
-			assert.deepEqual(prefixData, data);
-		});
-
-		it('Index file load correct sitemap', async () => {
-			const data = await readXML(fixture.readFile('/client/sitemap-index.xml'));
-			const sitemapUrl = data.sitemapindex.sitemap[0].loc[0];
-			assert.strictEqual(sitemapUrl, 'http://example.com/sitemap-0.xml');
-
-			const prefixData = await readXML(fixture.readFile(`/client/${prefix}index.xml`));
-			const prefixSitemapUrl = prefixData.sitemapindex.sitemap[0].loc[0];
-			assert.strictEqual(prefixSitemapUrl, `http://example.com/${prefix}0.xml`);
-		});
-	});
-});