diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index cee90a1..4a1a726 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -3186,6 +3186,7 @@
   tls13_default = 0,
   tls13_experiment = 1,
   tls13_record_type_experiment = 2,
+  tls13_no_session_id_experiment = 3,
 };
 
 /* SSL_CTX_set_tls13_variant sets which variant of TLS 1.3 we negotiate. On the