diff --git a/draft-ietf-tls-esni.md b/draft-ietf-tls-esni.md
index 6786057e..fcd1c4c7 100644
--- a/draft-ietf-tls-esni.md
+++ b/draft-ietf-tls-esni.md
@@ -216,9 +216,10 @@ The ECH configuration is defined by the following `ECHConfig` structure.
 
 ~~~~
     opaque HpkePublicKey<1..2^16-1>;
-    uint16 HpkeKemId;  // Defined in RFC9180
-    uint16 HpkeKdfId;  // Defined in RFC9180
-    uint16 HpkeAeadId; // Defined in RFC9180
+    uint16 HpkeKemId;              // Defined in RFC9180
+    uint16 HpkeKdfId;              // Defined in RFC9180
+    uint16 HpkeAeadId;             // Defined in RFC9180
+    uint16 ECHConfigExtensionType; // Defined in Section 11.3
 
     struct {
         HpkeKdfId kdf_id;