Port to Qt 6
diff --git a/ide/Notebook.h b/ide/Notebook.h
index 867c2e9..6a5d0cf 100644
--- a/ide/Notebook.h
+++ b/ide/Notebook.h
@@ -4,8 +4,7 @@
 
 #include "Cell.h"
 #include "NbRuntime.h"
-
-class CellModel;
+#include "CellModel.h"
 
 class Notebook : public QObject
 {