diff --git a/cpp/switchchain.cpp b/cpp/switchchain.cpp
index 46c0ec8fee28118b9e38a9a7f3e5bba08d96ba1b..c28de798386c5f684874bda92e5ab545330f8104 100644
--- a/cpp/switchchain.cpp
+++ b/cpp/switchchain.cpp
@@ -1,6 +1,7 @@
 #include "exports.hpp"
 #include "graph.hpp"
 #include "powerlaw.hpp"
+#include "graph_spectrum.hpp"
 #include <algorithm>
 #include <array>
 #include <fstream>