diff --git a/src/quic_conn.c b/src/quic_conn.c
index a110e9c23..832886260 100644
--- a/src/quic_conn.c
+++ b/src/quic_conn.c
@@ -2052,6 +2052,11 @@ static inline void qc_release_lost_pkts(struct quic_conn *qc,
 			qc->path->cc.algo->slow_start(&qc->path->cc);
 	}
 
+	/* <oldest_lost> cannot be NULL at this stage because we have ensured
+	 * that <pkts> list is not empty. Without this, GCC 12.2.0 reports a
+	 * possible overflow on a 0 byte region with O2 optimization.
+	 */
+	ALREADY_CHECKED(oldest_lost);
 	quic_tx_packet_refdec(oldest_lost);
 	if (newest_lost != oldest_lost)
 		quic_tx_packet_refdec(newest_lost);