diff --git a/GUI/View/Instrument/EditDistributionDialog.h b/GUI/View/Instrument/EditDistributionDialog.h
index f61e190637dce3b66562906e8faebda9b811e9a5..a3bbe9e223a87dd831ac45f6a301f4fbdc93e482 100644
--- a/GUI/View/Instrument/EditDistributionDialog.h
+++ b/GUI/View/Instrument/EditDistributionDialog.h
@@ -17,6 +17,7 @@
 
 #include "GUI/View/Tool/ID.h"
 #include <QDialog>
+#include <optional>
 
 class DistributionPlot;
 class DistributionSelector;