diff --git a/quic/test_tools/quic_connection_peer.cc b/quic/test_tools/quic_connection_peer.cc
index 100fe15..953e495 100644
--- a/quic/test_tools/quic_connection_peer.cc
+++ b/quic/test_tools/quic_connection_peer.cc
@@ -351,5 +351,11 @@
   return connection->current_packet_content_;
 }
 
+// static
+void QuicConnectionPeer::SetLastHeaderFormat(QuicConnection* connection,
+                                             PacketHeaderFormat format) {
+  connection->last_header_.form = format;
+}
+
 }  // namespace test
 }  // namespace quic
diff --git a/quic/test_tools/quic_connection_peer.h b/quic/test_tools/quic_connection_peer.h
index b82c1b3..ef7e630 100644
--- a/quic/test_tools/quic_connection_peer.h
+++ b/quic/test_tools/quic_connection_peer.h
@@ -138,6 +138,8 @@
   static bool SupportsReleaseTime(QuicConnection* connection);
   static QuicConnection::PacketContent GetCurrentPacketContent(
       QuicConnection* connection);
+  static void SetLastHeaderFormat(QuicConnection* connection,
+                                  PacketHeaderFormat format);
 };
 
 }  // namespace test