diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index dc4782e..34353da 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1341,6 +1341,12 @@
                                                                   *    This pointer owns the transform
                                                                   *    it references.                  */
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    /* The application data transform in TLS 1.3.
+     * This pointer owns the transform it references. */
+    mbedtls_ssl_transform *MBEDTLS_PRIVATE(transform_application);
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
     /*
      * Timers
      */