diff --git a/apps/opencs/view/render/cellwater.hpp b/apps/opencs/view/render/cellwater.hpp
index 6d533e2915..a7154e9cb2 100644
--- a/apps/opencs/view/render/cellwater.hpp
+++ b/apps/opencs/view/render/cellwater.hpp
@@ -6,6 +6,7 @@
 #include <osg/ref_ptr>
 
 #include <QObject>
+#include <QModelIndex>
 
 namespace osg
 {