diff --git a/src/util/dummy-client-face.hpp b/src/util/dummy-client-face.hpp
index 9f46ca6..8d47a75 100644
--- a/src/util/dummy-client-face.hpp
+++ b/src/util/dummy-client-face.hpp
@@ -135,6 +135,10 @@
   shared_ptr<Transport> m_transport;
 };
 
+template<>
+void
+DummyClientFace::receive(const lp::Nack& nack);
+
 shared_ptr<DummyClientFace>
 makeDummyClientFace(const DummyClientFace::Options& options = DummyClientFace::DEFAULT_OPTIONS);