diff --git a/quic/core/crypto/certificate_view.h b/quic/core/crypto/certificate_view.h
index 870beb7..13bb5ff 100644
--- a/quic/core/crypto/certificate_view.h
+++ b/quic/core/crypto/certificate_view.h
@@ -113,7 +113,7 @@
 
 // Parses a DER time based on the specified ASN.1 tag.  Exposed primarily for
 // testing.
-quiche::QuicheOptional<quic::QuicWallTime> ParseDerTime(
+QUIC_EXPORT_PRIVATE quiche::QuicheOptional<quic::QuicWallTime> ParseDerTime(
     unsigned tag,
     quiche::QuicheStringPiece payload);