diff --git a/quiche/quic/core/http/quic_spdy_session.h b/quiche/quic/core/http/quic_spdy_session.h
index 0f4d0cc..65874b7 100644
--- a/quiche/quic/core/http/quic_spdy_session.h
+++ b/quiche/quic/core/http/quic_spdy_session.h
@@ -93,7 +93,7 @@
       QuicStreamId /*stream_id*/,
       QuicByteCount /*compressed_headers_length*/) = 0;
   virtual void OnHeadersDecoded(QuicStreamId /*stream_id*/,
-                                QuicHeaderList /*headers*/) = 0;
+                                const QuicHeaderList& /*headers*/) = 0;
 
   // Incoming HTTP/3 frames of unknown type on any stream.
   virtual void OnUnknownFrameReceived(QuicStreamId /*stream_id*/,
diff --git a/quiche/quic/test_tools/quic_test_utils.h b/quiche/quic/test_tools/quic_test_utils.h
index e1bf985..4673d3f 100644
--- a/quiche/quic/test_tools/quic_test_utils.h
+++ b/quiche/quic/test_tools/quic_test_utils.h
@@ -1049,7 +1049,7 @@
               (override));
   MOCK_METHOD(void, OnHeadersFrameReceived, (QuicStreamId, QuicByteCount),
               (override));
-  MOCK_METHOD(void, OnHeadersDecoded, (QuicStreamId, QuicHeaderList),
+  MOCK_METHOD(void, OnHeadersDecoded, (QuicStreamId, const QuicHeaderList&),
               (override));
   MOCK_METHOD(void, OnUnknownFrameReceived,
               (QuicStreamId, uint64_t, QuicByteCount), (override));