diff --git a/packages/integrations/sitemap/README.md b/packages/integrations/sitemap/README.md
index ab880a075..fda6577e8 100644
--- a/packages/integrations/sitemap/README.md
+++ b/packages/integrations/sitemap/README.md
@@ -141,7 +141,7 @@ export default {
 
 ### entryLimit
 
-Non-negative `Number` of entries per sitemap file. Default value is 45000. A sitemap index and multiple sitemaps are created if you have more entries. See explanation on [Google](https://developers.google.com/search/docs/advanced/sitemaps/large-sitemaps).
+Non-negative `Number` of entries per sitemap file. Default value is 45000. A sitemap index and multiple sitemaps are created if you have more entries. See explanation about large sitemaps on [Google](https://developers.google.com/search/docs/advanced/sitemaps/large-sitemaps).
 
 __astro.config.mjs__
 
@@ -166,7 +166,7 @@ export default {
 
 `lastmod` - The date of page last modification.  
 
-`changefreq` and `priority` are ignored by Google.  
+The `changefreq` and `priority` are ignored by Google.  
 
 See detailed explanation of sitemap specific options on [sitemap.org](https://www.sitemaps.org/protocol.html).  
 
@@ -194,12 +194,12 @@ export default {
 
 Async or sync function called for each sitemap entry just before writing to a disk.  
 
-It receives as parameter `SitemapItem` object which consists of `url` (required, absolute page URL) and optional `changefreq`, `lastmod`, `priority` and `links` properties.  
+It receives as parameter a `SitemapItem` object which consists of `url` (required, absolute page URL) and optional `changefreq`, `lastmod` (ISO formatted date, `String` type), `priority` and `links` properties.  
 
-Optional `links` property contains a `LinkItem` list of alternate pages including a parent page.  
-`LinkItem` type has two required fields: `url` (the fully-qualified URL for the version of this page for the specified language) and `hreflang` (a supported language code targeted by this version of the page).
+Optional `links` property contains the `LinkItem` list of alternate pages including a parent page.  
+The `LinkItem` type has two required fields: `url` (the fully-qualified URL for the version of this page for the specified language) and `lang` (a supported language code targeted by this version of the page).
 
-`serialize` function should return `SitemapItem`, touched or not.
+The `serialize` function should return `SitemapItem`, touched or not.  
 
 The example below shows the ability to add the sitemap specific properties individually.
 
diff --git a/packages/integrations/sitemap/src/constants.ts b/packages/integrations/sitemap/src/constants.ts
deleted file mode 100644
index 431cc5954..000000000
--- a/packages/integrations/sitemap/src/constants.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-export const changefreqValues = [
-	'always',
-	'hourly',
-	'daily',
-	'weekly',
-	'monthly',
-	'yearly',
-	'never',
-] as const;
diff --git a/packages/integrations/sitemap/src/generate-sitemap.ts b/packages/integrations/sitemap/src/generate-sitemap.ts
index 3c39e1f7e..0a5318c31 100644
--- a/packages/integrations/sitemap/src/generate-sitemap.ts
+++ b/packages/integrations/sitemap/src/generate-sitemap.ts
@@ -1,19 +1,16 @@
-import { SitemapItemLoose } from 'sitemap';
-
-import type { SitemapOptions } from './index';
+import type { SitemapOptions, SitemapItem } from './index';
 import { parseUrl } from './utils/parse-url';
 
 const STATUS_CODE_PAGE_REGEXP = /\/[0-9]{3}\/?$/;
 
 /** Construct sitemap.xml given a set of URLs */
 export function generateSitemap(pages: string[], finalSiteUrl: string, opts: SitemapOptions) {
-	const { changefreq, priority: prioritySrc, lastmod: lastmodSrc, i18n } = opts || {};
+	const { changefreq, priority, lastmod: lastmodSrc, i18n } = opts!;
 	// TODO: find way to respect <link rel="canonical"> URLs here
 	const urls = [...pages].filter((url) => !STATUS_CODE_PAGE_REGEXP.test(url));
 	urls.sort((a, b) => a.localeCompare(b, 'en', { numeric: true })); // sort alphabetically so sitemap is same each time
 
 	const lastmod = lastmodSrc?.toISOString();
-	const priority = typeof prioritySrc === 'number' ? prioritySrc : undefined;
 
 	const { locales, defaultLocale } = i18n || {};
 	const localeCodes = Object.keys(locales || {});
@@ -27,7 +24,7 @@ export function generateSitemap(pages: string[], finalSiteUrl: string, opts: Sit
 		return result?.locale;
 	};
 
-	const urlData = urls.map((url) => {
+	const urlData: SitemapItem[] = urls.map((url) => {
 		let links;
 		if (defaultLocale && locales) {
 			const currentPath = getPath(url);
@@ -47,8 +44,8 @@ export function generateSitemap(pages: string[], finalSiteUrl: string, opts: Sit
 			links,
 			lastmod,
 			priority,
-			changefreq, // : changefreq as EnumChangefreq,
-		} as SitemapItemLoose;
+			changefreq,
+		};
 	});
 
 	return urlData;
diff --git a/packages/integrations/sitemap/src/index.ts b/packages/integrations/sitemap/src/index.ts
index d35d635ca..d0888d302 100644
--- a/packages/integrations/sitemap/src/index.ts
+++ b/packages/integrations/sitemap/src/index.ts
@@ -1,14 +1,13 @@
 import type { AstroConfig, AstroIntegration } from 'astro';
-import { LinkItem as LinkItemBase, simpleSitemapAndIndex, SitemapItemLoose } from 'sitemap';
+import { LinkItem as LinkItemBase, simpleSitemapAndIndex, SitemapItemLoose, EnumChangefreq } from 'sitemap';
 import { fileURLToPath } from 'url';
 import { ZodError } from 'zod';
 
-import { changefreqValues } from './constants';
 import { generateSitemap } from './generate-sitemap';
 import { Logger } from './utils/logger';
 import { validateOptions } from './validate-options';
 
-export type ChangeFreq = typeof changefreqValues[number];
+export type ChangeFreq = EnumChangefreq;
 export type SitemapItem = Pick<
 	SitemapItemLoose,
 	'url' | 'lastmod' | 'changefreq' | 'priority' | 'links'
@@ -34,7 +33,7 @@ export type SitemapOptions =
 			priority?: number;
 
 			// called for each sitemap item just before to save them on disk, sync or async
-			serialize?(item: SitemapItemLoose): SitemapItemLoose;
+			serialize?(item: SitemapItem): SitemapItem | Promise<SitemapItem>;
 	  }
 	| undefined;
 
@@ -103,7 +102,7 @@ const createPlugin = (options?: SitemapOptions): AstroIntegration => {
 
 					if (serialize) {
 						try {
-							const serializedUrls: SitemapItemLoose[] = [];
+							const serializedUrls: SitemapItem[] = [];
 							for (const item of urlData) {
 								const serialized = await Promise.resolve(serialize(item));
 								serializedUrls.push(serialized);
diff --git a/packages/integrations/sitemap/src/schema.ts b/packages/integrations/sitemap/src/schema.ts
index e8c198ced..3175a2e28 100644
--- a/packages/integrations/sitemap/src/schema.ts
+++ b/packages/integrations/sitemap/src/schema.ts
@@ -1,47 +1,39 @@
 import { z } from 'zod';
+import { EnumChangefreq as ChangeFreq } from 'sitemap';
 import { SITEMAP_CONFIG_DEFAULTS } from './config-defaults';
-import { changefreqValues } from './constants';
 
-const localeKeySchema = () => z.string().min(1);
-
-const isFunction = (fn: any) => fn instanceof Function;
-
-const fnSchema = () =>
-	z
-		.any()
-		.refine((val) => !val || isFunction(val), { message: 'Not a function' })
-		.optional();
+const localeKeySchema = z.string().min(1);
 
 export const SitemapOptionsSchema = z
-	.object({
-		filter: fnSchema(),
-		customPages: z.string().url().array().optional(),
-		canonicalURL: z.string().url().optional(),
+  .object({
+    filter: z.function().args(z.string()).returns(z.boolean()).optional(),
+    customPages: z.string().url().array().optional(),
+    canonicalURL: z.string().url().optional(),
 
-		i18n: z
-			.object({
-				defaultLocale: localeKeySchema(),
-				locales: z.record(
-					localeKeySchema(),
-					z
-						.string()
-						.min(2)
-						.regex(/^[a-zA-Z\-]+$/gm, {
-							message: 'Only English alphabet symbols and hyphen allowed',
-						})
-				),
-			})
-			.refine((val) => !val || val.locales[val.defaultLocale], {
-				message: '`defaultLocale` must exists in `locales` keys',
-			})
-			.optional(),
+    i18n: z
+      .object({
+        defaultLocale: localeKeySchema,
+        locales: z.record(
+          localeKeySchema,
+          z
+            .string()
+            .min(2)
+            .regex(/^[a-zA-Z\-]+$/gm, {
+              message: 'Only English alphabet symbols and hyphen allowed',
+            }),
+        ),
+      })
+      .refine((val) => !val || val.locales[val.defaultLocale], {
+        message: '`defaultLocale` must exist in `locales` keys',
+      })
+      .optional(),
 
-		entryLimit: z.number().nonnegative().default(SITEMAP_CONFIG_DEFAULTS.entryLimit),
-		serialize: fnSchema(),
+    entryLimit: z.number().nonnegative().optional().default(SITEMAP_CONFIG_DEFAULTS.entryLimit),
+    serialize: z.function().args(z.any()).returns(z.any()).optional(),
 
-		changefreq: z.enum(changefreqValues).optional(),
-		lastmod: z.date().optional(),
-		priority: z.number().min(0).max(1).optional(),
-	})
-	.strict()
-	.default(SITEMAP_CONFIG_DEFAULTS);
+    changefreq: z.nativeEnum(ChangeFreq).optional(),
+    lastmod: z.date().optional(),
+    priority: z.number().min(0).max(1).optional(),
+  })
+  .strict()
+  .default(SITEMAP_CONFIG_DEFAULTS);