diff --git a/library/ssl_client.c b/library/ssl_client.c
index 0c32f07..22ca57c 100644
--- a/library/ssl_client.c
+++ b/library/ssl_client.c
@@ -308,110 +308,6 @@
 #endif /* MBEDTLS_ECDH_C || MBEDTLS_ECDSA_C ||
           MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
 
-#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
-/*
- * Function for writing a signature algorithm extension.
- *
- * The `extension_data` field of signature algorithm contains  a `SignatureSchemeList`
- * value (TLS 1.3 RFC8446):
- *      enum {
- *         ....
- *        ecdsa_secp256r1_sha256( 0x0403 ),
- *        ecdsa_secp384r1_sha384( 0x0503 ),
- *        ecdsa_secp521r1_sha512( 0x0603 ),
- *         ....
- *      } SignatureScheme;
- *
- *      struct {
- *         SignatureScheme supported_signature_algorithms<2..2^16-2>;
- *      } SignatureSchemeList;
- *
- * The `extension_data` field of signature algorithm contains a `SignatureAndHashAlgorithm`
- * value (TLS 1.2 RFC5246):
- *      enum {
- *          none(0), md5(1), sha1(2), sha224(3), sha256(4), sha384(5),
- *          sha512(6), (255)
- *      } HashAlgorithm;
- *
- *      enum { anonymous(0), rsa(1), dsa(2), ecdsa(3), (255) }
- *        SignatureAlgorithm;
- *
- *      struct {
- *          HashAlgorithm hash;
- *          SignatureAlgorithm signature;
- *      } SignatureAndHashAlgorithm;
- *
- *      SignatureAndHashAlgorithm
- *        supported_signature_algorithms<2..2^16-2>;
- *
- * The TLS 1.3 signature algorithm extension was defined to be a compatible
- * generalization of the TLS 1.2 signature algorithm extension.
- * `SignatureAndHashAlgorithm` field of TLS 1.2 can be represented by
- * `SignatureScheme` field of TLS 1.3
- *
- */
-static int ssl_write_sig_alg_ext( mbedtls_ssl_context *ssl, unsigned char *buf,
-                                  const unsigned char *end, size_t *out_len )
-{
-    unsigned char *p = buf;
-    unsigned char *supported_sig_alg; /* Start of supported_signature_algorithms */
-    size_t supported_sig_alg_len = 0; /* Length of supported_signature_algorithms */
-
-    *out_len = 0;
-
-    MBEDTLS_SSL_DEBUG_MSG( 3, ( "adding signature_algorithms extension" ) );
-
-    /* Check if we have space for header and length field:
-     * - extension_type         (2 bytes)
-     * - extension_data_length  (2 bytes)
-     * - supported_signature_algorithms_length   (2 bytes)
-     */
-    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
-    p += 6;
-
-    /*
-     * Write supported_signature_algorithms
-     */
-    supported_sig_alg = p;
-    const uint16_t *sig_alg = mbedtls_ssl_get_sig_algs( ssl );
-    if( sig_alg == NULL )
-        return( MBEDTLS_ERR_SSL_BAD_CONFIG );
-
-    for( ; *sig_alg != MBEDTLS_TLS1_3_SIG_NONE; sig_alg++ )
-    {
-        if( ! mbedtls_ssl_sig_alg_is_supported( ssl, *sig_alg ) )
-            continue;
-        MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
-        MBEDTLS_PUT_UINT16_BE( *sig_alg, p, 0 );
-        p += 2;
-        MBEDTLS_SSL_DEBUG_MSG( 3, ( "signature scheme [%x]", *sig_alg ) );
-    }
-
-    /* Length of supported_signature_algorithms */
-    supported_sig_alg_len = p - supported_sig_alg;
-    if( supported_sig_alg_len == 0 )
-    {
-        MBEDTLS_SSL_DEBUG_MSG( 1, ( "No signature algorithms defined." ) );
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
-    }
-
-    /* Write extension_type */
-    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SIG_ALG, buf, 0 );
-    /* Write extension_data_length */
-    MBEDTLS_PUT_UINT16_BE( supported_sig_alg_len + 2, buf, 2 );
-    /* Write length of supported_signature_algorithms */
-    MBEDTLS_PUT_UINT16_BE( supported_sig_alg_len, buf, 4 );
-
-    /* Output the total length of signature algorithms extension. */
-    *out_len = p - buf;
-
-#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
-    ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SIG_ALG;
-#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
-    return( 0 );
-}
-#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
-
 static int ssl_write_client_hello_cipher_suites(
             mbedtls_ssl_context *ssl,
             unsigned char *buf,
@@ -721,7 +617,7 @@
 #endif
        0 )
     {
-        ret = ssl_write_sig_alg_ext( ssl, p, end, &output_len );
+        ret = mbedtls_ssl_write_sig_alg_ext( ssl, p, end, &output_len );
         if( ret != 0 )
             return( ret );
         p += output_len;