diff --git a/src/api/tojs.ts b/src/api/tojs.ts
index 67a3e19b3..886187c77 100644
--- a/src/api/tojs.ts
+++ b/src/api/tojs.ts
@@ -8,6 +8,9 @@ import {deprecated, isArrayLike} from "../utils/utils";
 /**
 	* Basically, a deep clone, so that no reactive property will exist anymore.
 	*/
+export function toJS<T>(source: T, detectCycles?: boolean): T;
+export function toJS(source: any, detectCycles?: boolean): any;
+export function toJS(source, detectCycles: boolean, __alreadySeen: [any, any][]); // internal overload
 export function toJS(source, detectCycles: boolean = true, __alreadySeen: [any, any][] = null) {
 	// optimization: using ES6 map would be more efficient!
 	// optimization: lift this function outside toJS, this makes recursion expensive