diff --git a/.changeset/blue-glasses-compete.md b/.changeset/blue-glasses-compete.md
new file mode 100644
index 000000000000..48fdd5011d78
--- /dev/null
+++ b/.changeset/blue-glasses-compete.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+[fix] ActionData type
diff --git a/packages/kit/types/index.d.ts b/packages/kit/types/index.d.ts
index 6b3d40651f93..655f6237a3a5 100644
--- a/packages/kit/types/index.d.ts
+++ b/packages/kit/types/index.d.ts
@@ -16,7 +16,7 @@ import {
 	TrailingSlash
 } from './private.js';
 import { SSRNodeLoader, SSRRoute, ValidatedConfig } from './internal.js';
-import { HttpError, Redirect, ValidationError } from '../src/runtime/control.js';
+import { HttpError, Redirect } from '../src/runtime/control.js';
 
 export { PrerenderOption } from './private.js';
 
@@ -39,6 +39,12 @@ export type AwaitedActions<T extends Record<string, (...args: any) => any>> = {
 	[Key in keyof T]: UnpackValidationError<Awaited<ReturnType<T[Key]>>>;
 }[keyof T];
 
+// Needs to be here, else ActionData will be resolved to unknown - probably because of "d.ts file imports .js file" in combination with allowJs
+interface ValidationError<T extends Record<string, unknown> | undefined = undefined> {
+	status: number;
+	data: T;
+}
+
 type UnpackValidationError<T> = T extends ValidationError<infer X> ? X : T;
 
 export interface Builder {