diff --git a/quiche/quic/core/quic_flags_list.h b/quiche/quic/core/quic_flags_list.h
index 0dedd71..f222234 100644
--- a/quiche/quic/core/quic_flags_list.h
+++ b/quiche/quic/core/quic_flags_list.h
@@ -104,7 +104,7 @@
 // When true, allows sending of QUIC packets marked ECT(1). A different flag (TBD) will actually utilize this capability to send ECT(1).
 QUIC_FLAG(quic_restart_flag_quic_support_ect1, false)
 // When true, correctly stores the ECN mark on incoming packets when buffered while waiting for a crypto context.
-QUIC_FLAG(quic_reloadable_flag_quic_clone_ecn, false)
+QUIC_FLAG(quic_reloadable_flag_quic_clone_ecn, true)
 // When true, defaults to BBR congestion control instead of Cubic.
 QUIC_FLAG(quic_reloadable_flag_quic_default_to_bbr, false)
 // When true, report received ECN markings to the peer. Replaces quic_receive_ecn2 to use correct codepoints.