diff --git a/quickevent/app/quickevent/plugins/Oris/src/xmlimporter.h b/quickevent/app/quickevent/plugins/Oris/src/xmlimporter.h
index ae44634d0..259ea4b24 100644
--- a/quickevent/app/quickevent/plugins/Oris/src/xmlimporter.h
+++ b/quickevent/app/quickevent/plugins/Oris/src/xmlimporter.h
@@ -8,6 +8,8 @@
 #include <QTime>
 #include <QDate>
 
+#include <optional>
+
 class XmlImporter : public QObject
 {
 	Q_OBJECT