diff --git a/src/build.ts b/src/build.ts
index 9f9f8f3ea..8310b1179 100644
--- a/src/build.ts
+++ b/src/build.ts
@@ -186,7 +186,7 @@ export async function build(astroConfig: AstroConfig): Promise<0 | 1> {
         const filepath = new URL(`file://${pathname}`);
 
         const pageType = getPageType(filepath);
-        const pageOptions: PageBuildOptions = { astroRoot, dist, filepath, runtime, sitemap: astroConfig.sitemap, statics };
+        const pageOptions: PageBuildOptions = { astroRoot, dist, filepath, runtime, sitemap: astroConfig.buildOptions.sitemap, statics };
         if (pageType === 'collection') {
           const { canonicalURLs } = await buildCollectionPage(pageOptions);
           builtURLs.push(...canonicalURLs);
@@ -239,7 +239,7 @@ export async function build(astroConfig: AstroConfig): Promise<0 | 1> {
   }
 
   // build sitemap
-  if (astroConfig.sitemap && astroConfig.site) {
+  if (astroConfig.buildOptions.sitemap && astroConfig.site) {
     const sitemap = generateSitemap(
       builtURLs.map((url) => ({
         canonicalURL: new URL(
@@ -249,7 +249,7 @@ export async function build(astroConfig: AstroConfig): Promise<0 | 1> {
       }))
     );
     await writeFile(new URL('./sitemap.xml', dist), sitemap, 'utf8');
-  } else if (astroConfig.sitemap) {
+  } else if (astroConfig.buildOptions.sitemap) {
     info(logging, 'tip', `Set your "site" in astro.config.mjs to generate a sitemap.xml`);
   }
 
diff --git a/src/config.ts b/src/config.ts
index af618a27f..5b77a3402 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -25,7 +25,7 @@ function validateConfig(config: any): void {
     }
   }
 
-  if(config.devOptions?.port !== 'number') {
+  if(typeof config.devOptions?.port !== 'number') {
     throw new Error(`[astro config] devOptions.port: Expected number, received ${type(config.devOptions?.port)}`)
   }
 }
@@ -40,7 +40,8 @@ function configDefaults(userConfig?: any): any {
   if (!config.public) config.public = './public';
   if (!config.devOptions) config.devOptions = {};
   if (!config.devOptions.port) config.devOptions.port = 3000;
-  if (typeof config.sitemap === 'undefined') config.sitemap = true;
+  if (!config.buildOptions) config.buildOptions = {};
+  if (typeof config.buildOptions.sitemap === 'undefined') config.buildOptions.sitemap = true;
 
   return config;
 }