diff --git a/packages/svelte/src/compiler/validate-options.js b/packages/svelte/src/compiler/validate-options.js
index e58b5deff324..a55258550d4d 100644
--- a/packages/svelte/src/compiler/validate-options.js
+++ b/packages/svelte/src/compiler/validate-options.js
@@ -83,6 +83,8 @@ export const validate_component_options =
 
 			namespace: list(['html', 'svg', 'foreign']),
 
+			modernAst: boolean(false),
+
 			outputFilename: string(undefined),
 
 			preserveComments: boolean(false),