diff --git a/ts-lib/test/common.ts b/ts-lib/test/common.ts
index 8ee2ac1..94fb581 100644
--- a/ts-lib/test/common.ts
+++ b/ts-lib/test/common.ts
@@ -1,3 +1,5 @@
+import { randomBytes } from "crypto";
+
 export const json_512kb = import("../../test/data/512KB.json");
 export const json_1mb = import("../../test/data/1MB.json");
 export const rw_medium = import("../../test/data/rw_medium.json");
@@ -14,20 +16,17 @@ export const TestData = [
 	{ name: "rw_large", input: JSON.stringify(await rw_large) },
 ];
 
-function getCrypto() {
+export function randomStr(len: number) {
 	try {
-		return window.crypto;
-	} catch {
-		return crypto;
+		var arr = new Uint8Array(len);
+		window.crypto.getRandomValues(arr);
+		return new TextDecoder().decode(arr);
+	} catch (e) {
+		const arr = randomBytes(len);
+		return new TextDecoder().decode(arr);
 	}
 }
 
-export function randomStr(len: number) {
-	var arr = new Uint8Array(len);
-	getCrypto().getRandomValues(arr);
-	return new TextDecoder().decode(arr);
-}
-
 for (let i = 0; i < 10; ++i) {
 	TestData.push({
 		name: `Random string #${i}`,