diff --git a/src/Umbraco.Web.UI.Client/libs/extensions-api/is-manifest-js-type.function.ts b/src/Umbraco.Web.UI.Client/libs/extensions-api/is-manifest-js-type.function.ts
index 5f4244f660..24962b7ec0 100644
--- a/src/Umbraco.Web.UI.Client/libs/extensions-api/is-manifest-js-type.function.ts
+++ b/src/Umbraco.Web.UI.Client/libs/extensions-api/is-manifest-js-type.function.ts
@@ -1,6 +1,6 @@
 import { ManifestJSType } from './load-extension.function';
 import type { ManifestBase } from '@umbraco-cms/extensions-registry';
 
-export function isManifestJSType(manifest: ManifestBase): manifest is ManifestJSType {
+export function isManifestJSType(manifest: ManifestBase | unknown): manifest is ManifestJSType {
 	return (manifest as ManifestJSType).js !== undefined;
 }