diff --git a/quic/core/crypto/crypto_protocol.h b/quic/core/crypto/crypto_protocol.h
index c4ea956..5a30038 100644
--- a/quic/core/crypto/crypto_protocol.h
+++ b/quic/core/crypto/crypto_protocol.h
@@ -433,6 +433,7 @@
 
 // Client Hints triggers.
 const QuicTag kGWCH = TAG('G', 'W', 'C', 'H');
+const QuicTag kYTCH = TAG('Y', 'T', 'C', 'H');
 
 // Rejection tags
 const QuicTag kRREJ = TAG('R', 'R', 'E', 'J');   // Reasons for server sending