diff --git a/src/main.ts b/src/main.ts
index cd60dde..d8c4aba 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -64,7 +64,7 @@ let liveRates: Record<string, number> = {};
 let lastWindowFocusAt = 0;
 
 function uid(): string {
-  return Math.random().toString(36).slice(2, 10);
+  return crypto.randomUUID();
 }
 
 // ---------- documents