diff --git a/01.md b/01.md
index 0e68de5e..eead9664 100644
--- a/01.md
+++ b/01.md
@@ -89,7 +89,7 @@ The `limit` property of a filter is only valid for the initial query and can be
 Relays can send 2 types of messages, which must also be JSON arrays, according to the following patterns:
 
   * `["EVENT", <subscription_id>, <event JSON as defined above>]`, used to send events requested by clients.
-  * `["NOTICE", <message>]`, used to send human-readable error messages or other things to clients.
+  * `["NOTICE", <message>, <subscription_id>]`, used to send human-readable error messages or other things to clients. Relays might optionally send a `subscription_id` this notice was caused by.
 
 This NIP defines no rules for how `NOTICE` messages should be sent or treated.