diff --git a/Polyhedron/demo/Polyhedron/Viewer.cpp b/Polyhedron/demo/Polyhedron/Viewer.cpp
index a1779cefa28..ec6f374323c 100644
--- a/Polyhedron/demo/Polyhedron/Viewer.cpp
+++ b/Polyhedron/demo/Polyhedron/Viewer.cpp
@@ -17,6 +17,7 @@
 #include <QOpenGLDebugLogger>
 #include <QStyleFactory>
 #include <QAction>
+#include <QRegularExpressionMatch>
 #ifdef CGAL_USE_WEBSOCKETS
 #include <QtWebSockets/QWebSocket>
 #endif