diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 53c519c..919db7d 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -318,6 +318,7 @@
             ssl, group_id, p, end, &key_exchange_len);
         p += key_exchange_len;
         if (ret != 0) {
+            MBEDTLS_SSL_DEBUG_MSG(1, ("client hello: failed generating xxdh key exchange"));
             return ret;
         }