diff --git a/packages/astro/src/core/config/schema.ts b/packages/astro/src/core/config/schema.ts
index afb49c0538..dd21289cc3 100644
--- a/packages/astro/src/core/config/schema.ts
+++ b/packages/astro/src/core/config/schema.ts
@@ -210,17 +210,24 @@ export const AstroConfigSchema = z.object({
 			middleware: z.oboolean().optional().default(ASTRO_CONFIG_DEFAULTS.experimental.middleware),
 			hybridOutput: z.boolean().optional().default(ASTRO_CONFIG_DEFAULTS.experimental.hybridOutput),
 		})
-    .passthrough()
-    .refine(d => {
-      const validKeys = Object.keys(ASTRO_CONFIG_DEFAULTS.experimental)
-      const invalidKeys = Object.keys(d).filter(key => !validKeys.includes(key))
-      if (invalidKeys.length > 0) return false
-      return true
-    }, d => {
-      const validKeys = Object.keys(ASTRO_CONFIG_DEFAULTS.experimental)
-      const invalidKeys = Object.keys(d).filter(key => !validKeys.includes(key))
-      return { message: `Invalid experimental key: \`${invalidKeys.join(', ')}\`. \nMake sure the spelling is correct, and that your Astro version supports this experiment.\nSee https://docs.astro.build/en/reference/configuration-reference/#experimental-flags for more information.` };
-    })
+		.passthrough()
+		.refine(
+			(d) => {
+				const validKeys = Object.keys(ASTRO_CONFIG_DEFAULTS.experimental);
+				const invalidKeys = Object.keys(d).filter((key) => !validKeys.includes(key));
+				if (invalidKeys.length > 0) return false;
+				return true;
+			},
+			(d) => {
+				const validKeys = Object.keys(ASTRO_CONFIG_DEFAULTS.experimental);
+				const invalidKeys = Object.keys(d).filter((key) => !validKeys.includes(key));
+				return {
+					message: `Invalid experimental key: \`${invalidKeys.join(
+						', '
+					)}\`. \nMake sure the spelling is correct, and that your Astro version supports this experiment.\nSee https://docs.astro.build/en/reference/configuration-reference/#experimental-flags for more information.`,
+				};
+			}
+		)
 		.optional()
 		.default({}),
 	legacy: z.object({}).optional().default({}),