diff --git a/lib/index.ts b/lib/index.ts
index 0835321..e5b4627 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -117,7 +117,7 @@ export function decodeTime(id: string): number {
 
 export function detectPrng(allowInsecure: boolean = false, root?: any): PRNG {
   if (!root) {
-    root = typeof window !== "undefined" ? window : null
+    root = typeof self !== "undefined" ? self : null
   }
 
   const browserCrypto = root && (root.crypto || root.msCrypto)