diff --git a/quiche/common/quiche_feature_flags_list.h b/quiche/common/quiche_feature_flags_list.h
index 4e79786..37f799c 100755
--- a/quiche/common/quiche_feature_flags_list.h
+++ b/quiche/common/quiche_feature_flags_list.h
@@ -40,7 +40,7 @@
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_enforce_immediate_goaway, false, true, "If true, QUIC will support sending immediate GOAWAYS and will refuse streams above the limit.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_enobufs_blocked, true, true, "If true, ENOBUFS socket errors are reported as socket blocked instead of socket failure.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_fin_before_completed_http_headers, false, true, "If true, close the connection with error if FIN is received before finish receiving the whole HTTP headers.")
-QUICHE_FLAG(bool, quiche_reloadable_flag_quic_fix_mtu_discovery, true, true, "If true, fix a externally reported bug in QUIC MTU discovery.")
+QUICHE_FLAG(bool, quiche_reloadable_flag_quic_fix_mtu_discovery, false, true, "If true, fix a externally reported bug in QUIC MTU discovery.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_fix_timeouts, true, true, "If true, postpone setting handshake timeout to infinite to handshake complete.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_include_datagrams_in_willing_to_write, false, false, "If true, checks for queued datagrams when determining if a connection is willing to write.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_maybe_copy_datagram_frames, false, true, "If true, maybe copy datagram frames in QuicUnackedPacketMap.")