diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 7fec65e..5869e15 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -138,6 +138,7 @@
 #define MBEDTLS_SSL_MINOR_VERSION_1             1   /*!< TLS v1.0 */
 #define MBEDTLS_SSL_MINOR_VERSION_2             2   /*!< TLS v1.1 */
 #define MBEDTLS_SSL_MINOR_VERSION_3             3   /*!< TLS v1.2 */
+#define MBEDTLS_SSL_MINOR_VERSION_4             4   /*!< TLS v1.3 (experimental) */
 
 #define MBEDTLS_SSL_TRANSPORT_STREAM            0   /*!< TLS      */
 #define MBEDTLS_SSL_TRANSPORT_DATAGRAM          1   /*!< DTLS     */