diff --git a/draft-ietf-quic-transport.md b/draft-ietf-quic-transport.md
index 19ee78bf3f..9463f748ab 100644
--- a/draft-ietf-quic-transport.md
+++ b/draft-ietf-quic-transport.md
@@ -4318,7 +4318,7 @@ preferred_address (0x000d):
      uint16 ipv4Port;
      opaque ipv6Address[16];
      uint16 ipv6Port;
-     opaque connectionId<0..18>;
+     opaque connectionId<0..20>;
      opaque statelessResetToken[16];
    } PreferredAddress;
 ~~~