diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 910f610..1d81333 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -88,7 +88,7 @@
 // If true, quic connection sends/recieives NewConnectionId & RetireConnectionId frames.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_connection_support_multiple_cids_v4, true)
 // If true, quic dispatcher discards packets with invalid server connection ID.
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_discard_packets_with_invalid_cid, false)
+QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_discard_packets_with_invalid_cid, true)
 // If true, quic dispatcher supports one connection to use multiple connection IDs. 
 QUIC_FLAG(FLAGS_quic_restart_flag_quic_dispatcher_support_multiple_cid_per_connection_v2, true)
 // If true, require handshake confirmation for QUIC connections, functionally disabling 0-rtt handshakes.