diff --git a/Qt/zoomableimage.cpp b/Qt/zoomableimage.cpp
index a04dfce..72cfc7b 100644
--- a/Qt/zoomableimage.cpp
+++ b/Qt/zoomableimage.cpp
@@ -17,6 +17,7 @@
  *
  */
 
+#include <functional>
 #include "zoomableimage.h"
 #include <QLabel>
 #include <QImage>