diff --git a/quiche/common/quiche_feature_flags_list.h b/quiche/common/quiche_feature_flags_list.h
index aea7910..ff2bc09 100755
--- a/quiche/common/quiche_feature_flags_list.h
+++ b/quiche/common/quiche_feature_flags_list.h
@@ -59,7 +59,7 @@
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_testonly_default_false, false, false, "A testonly reloadable flag that will always default to false.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_testonly_default_true, true, true, "A testonly reloadable flag that will always default to true.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_use_inlining_send_buffer2, true, true, "Uses an inlining version of QuicSendStreamBuffer.")
-QUICHE_FLAG(bool, quiche_reloadable_flag_quic_use_proof_source_get_cert_chains, false, false, "When true, quic::TlsServerHandshaker will use ProofSource::GetCertChains() instead of ProofSource::GetCertChain()")
+QUICHE_FLAG(bool, quiche_reloadable_flag_quic_use_proof_source_get_cert_chains, false, true, "When true, quic::TlsServerHandshaker will use ProofSource::GetCertChains() instead of ProofSource::GetCertChain()")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_use_received_client_addresses_cache, true, true, "If true, use a LRU cache to record client addresses of packets received on server's original address.")
 QUICHE_FLAG(bool, quiche_restart_flag_quic_dispatcher_close_connection_on_invalid_ack, false, false, "An invalid ack is an ack that the peer sent for a packet that was not sent by the dispatcher. If true, the dispatcher will close the connection if it receives an invalid ack.")
 QUICHE_FLAG(bool, quiche_restart_flag_quic_shed_tls_handshake_config, false, false, "If true, QUIC connections will call SSL_set_shed_handshake_config to drop BoringSSL handshake state after the handshake finishes in order to save memory.")