diff --git a/quic/test_tools/failing_proof_source.h b/quic/test_tools/failing_proof_source.h
index 36e2398..69a3e7a 100644
--- a/quic/test_tools/failing_proof_source.h
+++ b/quic/test_tools/failing_proof_source.h
@@ -30,6 +30,8 @@
       uint16_t signature_algorithm,
       quiche::QuicheStringPiece in,
       std::unique_ptr<SignatureCallback> callback) override;
+
+  TicketCrypter* SessionTicketCrypter() override { return nullptr; }
 };
 
 }  // namespace test