diff --git a/src/ThreadVisualisation.h b/src/ThreadVisualisation.h
index d36f42f446f08ad7bf4969c77f000299a699d177..7abc79132bf4414b9942bc9fd7b26f975d8ed0d2 100644
--- a/src/ThreadVisualisation.h
+++ b/src/ThreadVisualisation.h
@@ -45,6 +45,7 @@
 // forwarded classes
 class QThread;
 class QObject;
+class QColor;
 
 class vtkRenderer;
 class vtkAssembly;