diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 51a3a06..eed4413 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -349,6 +349,8 @@
 
 #define MBEDTLS_TLS_EXT_SESSION_TICKET              35
 
+#define MBEDTLS_TLS_EXT_ECJPAKE_KKPP               256 /* experimental */
+
 #define MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      0xFF01
 
 /*