diff --git a/src/quic_tx.c b/src/quic_tx.c
index 7f5647e81..ac331ae94 100644
--- a/src/quic_tx.c
+++ b/src/quic_tx.c
@@ -439,7 +439,8 @@ static int qc_send_ppkts(struct buffer *buf, struct quic_conn *qc)
 			}
 			qc->path->in_flight += pkt->in_flight_len;
 			pkt->pktns->tx.in_flight += pkt->in_flight_len;
-			if (quic_tune_test(QUIC_TUNE_FB_CC_HYSTART, qc) && pkt->pktns == qc->apktns)
+			if (quic_tune_test(QUIC_TUNE_FB_CC_HYSTART, qc) && pkt->pktns == qc->apktns &&
+			    cc->algo->hystart_start_round != NULL)
 				cc->algo->hystart_start_round(cc, pkt->pn_node.key);
 			if (pkt->in_flight_len)
 				qc_set_timer(qc);