diff --git a/packages/astro/src/core/config.ts b/packages/astro/src/core/config.ts
index 4ed2c52c9a4f..05f1b1ae9550 100644
--- a/packages/astro/src/core/config.ts
+++ b/packages/astro/src/core/config.ts
@@ -339,7 +339,7 @@ export async function validateConfig(
 	const result = {
 		...(await AstroConfigRelativeSchema.parseAsync(userConfig)),
 		_ctx: {
-			pageExtensions: [],
+			pageExtensions: ['.astro', '.md'],
 			scripts: [],
 			renderers: [],
 			injectedRoutes: [],