diff --git a/quic/test_tools/quic_test_client.cc b/quic/test_tools/quic_test_client.cc
index d7f2033..5b93de5 100644
--- a/quic/test_tools/quic_test_client.cc
+++ b/quic/test_tools/quic_test_client.cc
@@ -82,6 +82,7 @@
       const ProofVerifyContext* /*context*/,
       std::string* /*error_details*/,
       std::unique_ptr<ProofVerifyDetails>* /*details*/,
+      uint8_t* /*out_alert*/,
       std::unique_ptr<ProofVerifierCallback> /*callback*/) override {
     return ProcessCerts(certs, cert_sct);
   }