diff --git a/quic/core/crypto/crypto_protocol.h b/quic/core/crypto/crypto_protocol.h
index 1534c97..f2033e1 100644
--- a/quic/core/crypto/crypto_protocol.h
+++ b/quic/core/crypto/crypto_protocol.h
@@ -125,6 +125,7 @@
 const QuicTag kIW10 = TAG('I', 'W', '1', '0');   // Force ICWND to 10
 const QuicTag kIW20 = TAG('I', 'W', '2', '0');   // Force ICWND to 20
 const QuicTag kIW50 = TAG('I', 'W', '5', '0');   // Force ICWND to 50
+const QuicTag kB2ON = TAG('B', '2', 'O', 'N');   // Enable BBRv2
 const QuicTag kNTLP = TAG('N', 'T', 'L', 'P');   // No tail loss probe
 const QuicTag k1TLP = TAG('1', 'T', 'L', 'P');   // 1 tail loss probe
 const QuicTag k1RTO = TAG('1', 'R', 'T', 'O');   // Send 1 packet upon RTO