diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 7009b73..1659aa2 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -156,6 +156,12 @@
                         + MBEDTLS_SSL_PADDING_ADD                \
                         )
 
+/* Maximum size in bytes of list in sig-hash algorithm ext., RFC 5246 */
+#define MBEDTLS_SSL_MAX_SIG_HASH_ALG_LIST_LEN  65534
+
+/* Maximum size in bytes of list in supported elliptic curve ext., RFC 4492 */
+#define MBEDTLS_SSL_MAX_CURVE_LIST_LEN         65535
+
 /*
  * Check that we obey the standard's message size bounds
  */