| diff --git a/lib/quicly.c b/lib/quicly.c | |
| index 82ba627..8c0163e 100644 | |
| --- a/lib/quicly.c | |
| +++ b/lib/quicly.c | |
| @@ -4713,7 +4713,7 @@ static int handle_ack_frame(quicly_conn_t *conn, struct st_quicly_handle_payload | |
| /* process newly acked packet */ | |
| if (state->epoch != sent->ack_epoch) | |
| return QUICLY_TRANSPORT_ERROR_PROTOCOL_VIOLATION; | |
| - int is_late_ack = 0; | |
| + int __attribute__((unused)) is_late_ack = 0; | |
| if (sent->ack_eliciting) { | |
| includes_ack_eliciting = 1; | |
| if (sent->cc_bytes_in_flight == 0) { |