diff --git a/backend_qt/qzint.h b/backend_qt/qzint.h
index d57ab6a..62fb0a4 100644
--- a/backend_qt/qzint.h
+++ b/backend_qt/qzint.h
@@ -19,6 +19,7 @@
 #ifndef QZINT_H
 #define QZINT_H
 
+#include <QObject>
 #include <QColor>
 #include <QPainter>
 #include "zint.h"