diff --git a/lib/randomSupplies.js b/lib/randomSupplies.js
index 617c4f0..0c5b95b 100644
--- a/lib/randomSupplies.js
+++ b/lib/randomSupplies.js
@@ -25,8 +25,9 @@
 		}
 		return window.location.host;
 	}
+
+	var persistentRnd = Object.create(null);
 	const getPersistentRnd = (function(){
-		var persistentRnd = Object.create(null);
 		
 		browser.runtime.onMessage.addListener(function(data){
 			if (data["canvasBlocker-set-domain-rnd"]){
@@ -51,6 +52,9 @@
 	}());
 	scope.persistent = {
 		name: "persistent",
+		setDomainRnd: function(domain, rnd){
+			persistentRnd[domain] = new Uint8Array(rnd);
+		},
 		getRng: function(length, window){
 			var bitSet = getPersistentRnd(window);