diff --git a/packages/astro/src/@types/astro.ts b/packages/astro/src/@types/astro.ts
index 6c409224a5..6481f88be7 100644
--- a/packages/astro/src/@types/astro.ts
+++ b/packages/astro/src/@types/astro.ts
@@ -784,7 +784,7 @@ export interface AstroUserConfig {
 		/**
 		 * @docs
 		 * @name build.format
-		 * @typeraw {('file' | 'directory')}
+		 * @typeraw {('file' | 'directory' | 'preserve')}
 		 * @default `'directory'`
 		 * @description
 		 * Control the output file format of each page. This value may be set by an adapter for you.