diff --git a/transport.go b/transport.go
index ccbe32c2..4988bcfe 100644
--- a/transport.go
+++ b/transport.go
@@ -54,7 +54,8 @@ type Transport struct {
 	Conn net.PacketConn
 
 	// The length of the connection ID in bytes.
-	// It can be 0, or any value between 4 and 18.
+	// It can be any value between 1 and 20.
+	// Due to the increased risk of collisions, it is not recommended to use connection IDs shorter than 4 bytes.
 	// If unset, a 4 byte connection ID will be used.
 	ConnectionIDLength int