diff -Naur a/src/luamm.hh b/src/luamm.hh
--- a/src/luamm.hh	2017-07-07 15:05:28.250032963 +0200
+++ b/src/luamm.hh	2017-07-07 15:05:43.230033134 +0200
@@ -28,6 +28,7 @@
 #include <exception>
 #include <stdexcept>
 #include <string>
+#include <functional>
 
 #include <lua.hpp>