diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 9fc8041262..f070b0fade 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -156,6 +156,15 @@ static int ssl_write_hostname_ext( mbedtls_ssl_context *ssl,
 
     return( 0 );
 }
+
+int mbedtls_ssl_write_hostname_ext( mbedtls_ssl_context *ssl,
+                                    unsigned char *buf,
+                                    const unsigned char *end,
+                                    size_t *olen )
+{
+    return ssl_write_hostname_ext( ssl, buf, end, olen );
+}
+
 #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
 
 #if defined(MBEDTLS_SSL_RENEGOTIATION)
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index c7d966bf2c..87347bf263 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -1037,6 +1037,13 @@ void mbedtls_ssl_set_inbound_transform( mbedtls_ssl_context *ssl,
 void mbedtls_ssl_set_outbound_transform( mbedtls_ssl_context *ssl,
                                          mbedtls_ssl_transform *transform );
 
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+int mbedtls_ssl_write_hostname_ext( mbedtls_ssl_context *ssl,
+                                    unsigned char *buf,
+                                    const unsigned char *end,
+                                    size_t *olen );
+#endif
+
 int mbedtls_ssl_handshake_client_step( mbedtls_ssl_context *ssl );
 int mbedtls_ssl_handshake_server_step( mbedtls_ssl_context *ssl );
 void mbedtls_ssl_handshake_wrapup( mbedtls_ssl_context *ssl );
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 9c8848454f..511f4cd289 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -798,6 +798,14 @@ static int ssl_tls13_write_client_hello_body( mbedtls_ssl_context *ssl,
 
 #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
 
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+    /* Write server name extention */
+    ret = mbedtls_ssl_write_hostname_ext( ssl, p, end, &output_len );
+    if( ret != 0 )
+        return( ret );
+    p += output_len;
+#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
+
     /* Add more extensions here */
 
     /* Write the length of the list of extensions. */