diff --git a/galmonmon.cc b/galmonmon.cc
index 9b56300..b602ca3 100644
--- a/galmonmon.cc
+++ b/galmonmon.cc
@@ -1,4 +1,4 @@
-
+#include <optional>
 #include "minicurl.hh"
 #include <iostream>
 #include "navmon.hh"