diff --git a/Polyhedron/demo/Polyhedron/MainWindow.h b/Polyhedron/demo/Polyhedron/MainWindow.h
index ca62da462b3..585455360a8 100644
--- a/Polyhedron/demo/Polyhedron/MainWindow.h
+++ b/Polyhedron/demo/Polyhedron/MainWindow.h
@@ -1,6 +1,6 @@
 #ifndef MAINWINDOW_H
 #define MAINWINDOW_H
-
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
 #include <QtOpenGL/qgl.h>
 #include <CGAL/Qt/DemosMainWindow.h>