diff --git a/src/changevaluedisplay.h b/src/changevaluedisplay.h
index 35bb84d..e4315cd 100644
--- a/src/changevaluedisplay.h
+++ b/src/changevaluedisplay.h
@@ -2,6 +2,7 @@
 
 // system includes
 #include <type_traits>
+#include <optional>
 
 // 3rdparty lib includes
 #include <espchrono.h>
diff --git a/src/menudisplay.h b/src/menudisplay.h
index f156512..4559a12 100644
--- a/src/menudisplay.h
+++ b/src/menudisplay.h
@@ -8,6 +8,7 @@
 #include <functional>
 #include <cassert>
 #include <memory>
+#include <optional>
 
 // 3rdparty lib includes
 #include <espchrono.h>