diff --git a/packages/astro/src/core/create-vite.ts b/packages/astro/src/core/create-vite.ts
index 36978ba502cb..96fdaa284156 100644
--- a/packages/astro/src/core/create-vite.ts
+++ b/packages/astro/src/core/create-vite.ts
@@ -143,7 +143,7 @@ export async function createVite(
 		},
 		plugins: [
 			await serializedManifestPlugin({ settings }),
-			await astroPluginRoutes({ settings, logger, fsMod: fs }),
+			await astroPluginRoutes({ settings, logger, fsMod: fs, command }),
 			astroVirtualManifestPlugin(),
 			configAliasVitePlugin({ settings }),
 			astroLoadFallbackPlugin({ fs, root: settings.config.root }),
diff --git a/packages/astro/src/core/routing/manifest/create.ts b/packages/astro/src/core/routing/manifest/create.ts
index a66cb99bcbe7..0e337b79ebac 100644
--- a/packages/astro/src/core/routing/manifest/create.ts
+++ b/packages/astro/src/core/routing/manifest/create.ts
@@ -465,7 +465,17 @@ function detectRouteCollision(a: RouteData, b: RouteData, _config: AstroConfig,
 export async function createRoutesList(
 	params: CreateRouteManifestParams,
 	logger: Logger,
-	{ dev = false }: { dev?: boolean } = {},
+	{
+		dev = false,
+		skipBuildOutputAssignment = false,
+	}: {
+		dev?: boolean;
+		/**
+		 * When `true`, the assignment of `settings.buildOutput` is skipped.
+		 * Usually, that's needed when this function has already been called.
+		 */
+		skipBuildOutputAssignment?: boolean;
+	} = {},
 ): Promise<RoutesList> {
 	const { settings } = params;
 	const { config } = settings;
@@ -494,7 +504,9 @@ export async function createRoutesList(
 		...[...filteredFiledBasedRoutes, ...injectedRoutes, ...redirectRoutes].sort(routeComparator),
 	];
 
-	settings.buildOutput = getPrerenderDefault(config) ? 'static' : 'server';
+	if (!skipBuildOutputAssignment) {
+		settings.buildOutput = getPrerenderDefault(config) ? 'static' : 'server';
+	}
 
 	// Check the prerender option for each route
 	const limit = pLimit(10);
diff --git a/packages/astro/src/vite-plugin-routes/index.ts b/packages/astro/src/vite-plugin-routes/index.ts
index 186cf568dc77..faca87f32755 100644
--- a/packages/astro/src/vite-plugin-routes/index.ts
+++ b/packages/astro/src/vite-plugin-routes/index.ts
@@ -19,6 +19,7 @@ type Payload = {
 	settings: AstroSettings;
 	logger: Logger;
 	fsMod?: typeof fsMod;
+	command: 'dev' | 'build';
 };
 
 const ASTRO_ROUTES_MODULE_ID = 'astro:routes';
@@ -30,6 +31,7 @@ export default async function astroPluginRoutes({
 	settings,
 	logger,
 	fsMod,
+	command,
 }: Payload): Promise<Plugin> {
 	logger.debug('update', 'Re-calculate routes');
 	let routeList = await createRoutesList(
@@ -39,7 +41,7 @@ export default async function astroPluginRoutes({
 		},
 		logger,
 		// TODO: the caller should handle this
-		{ dev: true },
+		{ dev: true, skipBuildOutputAssignment: command === 'build' },
 	);
 
 	let serializedRouteInfo: SerializedRouteInfo[] = routeList.routes.map(