diff --git a/lights.js b/lights.js
index 2a57582..283d24b 100644
--- a/lights.js
+++ b/lights.js
@@ -36,7 +36,7 @@ export function set_pattern(pat) {
 }
 
 let functions = {
-  rand: 
+  rand: () => { return Math.floor(Math.random() * 256) }
 }
 
 function tick_pattern() {