diff --git a/include/widgets/wx_treebook.h b/include/widgets/wx_treebook.h
index 45c794e8f2..456e904728 100644
--- a/include/widgets/wx_treebook.h
+++ b/include/widgets/wx_treebook.h
@@ -24,6 +24,7 @@
 #ifndef WX_TREEBOOK_H
 #define WX_TREEBOOK_H
 
+#include <functional>
 #include <wx/treebook.h>
 
 class WX_TREEBOOK : public wxTreebook