diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 9fc8041262..8c5c0242be 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -89,10 +89,10 @@ static int ssl_conf_has_static_raw_psk( mbedtls_ssl_config const *conf )
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
-static int ssl_write_hostname_ext( mbedtls_ssl_context *ssl,
-                                   unsigned char *buf,
-                                   const unsigned char *end,
-                                   size_t *olen )
+int mbedtls_ssl_write_hostname_ext( mbedtls_ssl_context *ssl,
+                                    unsigned char *buf,
+                                    const unsigned char *end,
+                                    size_t *olen )
 {
     unsigned char *p = buf;
     size_t hostname_len;
@@ -1168,10 +1168,10 @@ static int ssl_write_client_hello( mbedtls_ssl_context *ssl )
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
 
 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
-    if( ( ret = ssl_write_hostname_ext( ssl, p + 2 + ext_len,
-                                        end, &olen ) ) != 0 )
+    if( ( ret = mbedtls_ssl_write_hostname_ext( ssl, p + 2 + ext_len,
+                                                end, &olen ) ) != 0 )
     {
-        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_hostname_ext", ret );
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_hostname_ext", ret );
         return( ret );
     }
     ext_len += olen;
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index 7ca460cf39..23d5970d91 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 869465c68c..e36e28d9d7 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 extension */
+    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. */