diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index 5c20f29..bac1178 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -66,6 +66,15 @@
     return( ret );
 }
 
+void mbedtls_ssl_tls13_add_hs_msg_to_checksum( mbedtls_ssl_context *ssl,
+                                               unsigned hs_type,
+                                               unsigned char const *msg,
+                                               size_t msg_len )
+{
+    mbedtls_ssl_tls13_add_hs_hdr_to_checksum( ssl, hs_type, msg_len );
+    ssl->handshake->update_checksum( ssl, msg, msg_len );
+}
+
 void mbedtls_ssl_tls13_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
                                                unsigned hs_type,
                                                size_t total_hs_len )