diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 14ac06c..97c60c8 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -7503,6 +7503,8 @@
 
     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;