diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 31d7daf..5b6aee1 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -116,163 +116,6 @@
 #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
 
 /*
- * Functions for writing supported_groups extension.
- *
- * Stucture of supported_groups:
- *      enum {
- *          secp256r1(0x0017), secp384r1(0x0018), secp521r1(0x0019),
- *          x25519(0x001D), x448(0x001E),
- *          ffdhe2048(0x0100), ffdhe3072(0x0101), ffdhe4096(0x0102),
- *          ffdhe6144(0x0103), ffdhe8192(0x0104),
- *          ffdhe_private_use(0x01FC..0x01FF),
- *          ecdhe_private_use(0xFE00..0xFEFF),
- *          (0xFFFF)
- *      } NamedGroup;
- *      struct {
- *          NamedGroup named_group_list<2..2^16-1>;
- *      } NamedGroupList;
- */
-#if defined(MBEDTLS_ECDH_C)
-/*
- * In versions of TLS prior to TLS 1.3, this extension was named
- * 'elliptic_curves' and only contained elliptic curve groups.
- */
-static int ssl_tls13_write_named_group_list_ecdhe( mbedtls_ssl_context *ssl,
-                                                   unsigned char *buf,
-                                                   unsigned char *end,
-                                                   size_t *out_len )
-{
-    unsigned char *p = buf;
-
-    *out_len = 0;
-
-    const uint16_t *group_list = mbedtls_ssl_get_groups( ssl );
-
-    if( group_list == NULL )
-        return( MBEDTLS_ERR_SSL_BAD_CONFIG );
-
-    for ( ; *group_list != 0; group_list++ )
-    {
-        const mbedtls_ecp_curve_info *curve_info;
-        curve_info = mbedtls_ecp_curve_info_from_tls_id( *group_list );
-        if( curve_info == NULL )
-            continue;
-
-        if( !mbedtls_ssl_tls13_named_group_is_ecdhe( *group_list ) )
-            continue;
-
-        MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2);
-        MBEDTLS_PUT_UINT16_BE( *group_list, p, 0 );
-        p += 2;
-
-        MBEDTLS_SSL_DEBUG_MSG( 3, ( "NamedGroup: %s ( %x )",
-                                    curve_info->name, *group_list ) );
-    }
-
-    *out_len = p - buf;
-
-    return( 0 );
-}
-#else
-static int ssl_tls13_write_named_group_list_ecdhe( mbedtls_ssl_context *ssl,
-                                            unsigned char *buf,
-                                            unsigned char *end,
-                                            size_t *out_len )
-{
-    ((void) ssl);
-    ((void) buf);
-    ((void) end);
-    *out_len = 0;
-    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
-}
-#endif /* MBEDTLS_ECDH_C */
-
-static int ssl_tls13_write_named_group_list_dhe( mbedtls_ssl_context *ssl,
-                                        unsigned char *buf,
-                                        unsigned char *end,
-                                        size_t *out_len )
-{
-    ((void) ssl);
-    ((void) buf);
-    ((void) end);
-    *out_len = 0;
-    MBEDTLS_SSL_DEBUG_MSG( 3, ( "write_named_group_dhe is not implemented" ) );
-    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
-}
-
-static int ssl_tls13_write_supported_groups_ext( mbedtls_ssl_context *ssl,
-                                                 unsigned char *buf,
-                                                 unsigned char *end,
-                                                 size_t *out_len )
-{
-    unsigned char *p = buf ;
-    unsigned char *named_group_list; /* Start of named_group_list */
-    size_t named_group_list_len;     /* Length of named_group_list */
-    size_t output_len = 0;
-    int ret_ecdhe, ret_dhe;
-
-    *out_len = 0;
-
-    if( !mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) )
-        return( 0 );
-
-    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding supported_groups extension" ) );
-
-    /* Check if we have space for header and length fields:
-     * - extension_type            (2 bytes)
-     * - extension_data_length     (2 bytes)
-     * - named_group_list_length   (2 bytes)
-     */
-    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
-    p += 6;
-
-    named_group_list = p;
-    ret_ecdhe = ssl_tls13_write_named_group_list_ecdhe( ssl, p, end, &output_len );
-    if( ret_ecdhe != 0 )
-    {
-        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_named_group_list_ecdhe", ret_ecdhe );
-    }
-    p += output_len;
-
-    ret_dhe = ssl_tls13_write_named_group_list_dhe( ssl, p, end, &output_len );
-    if( ret_dhe != 0 )
-    {
-        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_named_group_list_dhe", ret_dhe );
-    }
-    p += output_len;
-
-    /* Both ECDHE and DHE failed. */
-    if( ret_ecdhe != 0 && ret_dhe != 0 )
-    {
-        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Both ECDHE and DHE groups are fail. " ) );
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
-    }
-
-    /* Length of named_group_list*/
-    named_group_list_len = p - named_group_list;
-    if( named_group_list_len == 0 )
-    {
-        MBEDTLS_SSL_DEBUG_MSG( 1, ( "No group available." ) );
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
-    }
-
-    /* Write extension_type */
-    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_GROUPS, buf, 0 );
-    /* Write extension_data_length */
-    MBEDTLS_PUT_UINT16_BE( named_group_list_len + 2, buf, 2 );
-    /* Write length of named_group_list */
-    MBEDTLS_PUT_UINT16_BE( named_group_list_len, buf, 4 );
-
-    MBEDTLS_SSL_DEBUG_BUF( 3, "Supported groups extension", buf + 4, named_group_list_len + 2 );
-
-    *out_len = p - buf;
-
-    ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS;
-
-    return( 0 );
-}
-
-/*
  * Functions for writing key_share extension.
  */
 #if defined(MBEDTLS_ECDH_C)
@@ -777,7 +620,7 @@
      *
      * It is REQUIRED for ECDHE cipher_suites.
      */
-    ret = ssl_tls13_write_supported_groups_ext( ssl, p, end, &output_len );
+    ret = mbedtls_ssl_write_supported_groups_ext( ssl, p, end, &output_len );
     if( ret != 0 )
         return( ret );
     p += output_len;