diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 9f9ab72..d046495 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -630,7 +630,7 @@
             return( ret );
         p += output_len;
 
-        ret = mbedtls_ssl_tls13_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;