diff --git a/include/picotls.h b/include/picotls.h
index ea5c15e..2486ff3 100644
--- a/include/picotls.h
+++ b/include/picotls.h
@@ -168,6 +168,7 @@
 #define PTLS_ALERT_CERTIFICATE_UNKNOWN 46
 #define PTLS_ALERT_ILLEGAL_PARAMETER 47
 #define PTLS_ALERT_UNKNOWN_CA 48
+#define PTLS_ALERT_ACCESS_DENIED 49
 #define PTLS_ALERT_DECODE_ERROR 50
 #define PTLS_ALERT_DECRYPT_ERROR 51
 #define PTLS_ALERT_PROTOCOL_VERSION 70