diff --git a/01.md b/01.md
index eb9f60c1..622e4a23 100644
--- a/01.md
+++ b/01.md
@@ -108,6 +108,8 @@ These are just conventions and relay implementations may differ.
 
 Relays expose a websocket endpoint to which clients can connect. Clients SHOULD open a single websocket connection to each relay and use it for all their subscriptions. Relays MAY limit number of connections from specific IP/client/etc.
 
+Relays MUST only accept connections to a single endpoint when additional path segments do not influence its behavior.
+
 ### From client to relay: sending events and creating subscriptions
 
 Clients can send 3 types of messages, which must be JSON arrays, according to the following patterns: