diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 5d8d5c1..aa198ce 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -17,7 +17,7 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_reset_max_bytes_delivered, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_use_bytes_delivered, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_can_send_ack_frequency, true)
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_close_connection_on_0rtt_packet_number_higher_than_1rtt, false)
+QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_close_connection_on_0rtt_packet_number_higher_than_1rtt, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_close_connection_with_too_many_outstanding_packets, false)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_conservative_bursts, false)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_conservative_cwnd_and_pacing_gains, false)