diff --git a/src/Gui/SoMouseWheelEvent.h b/src/Gui/SoMouseWheelEvent.h
index 268009f397..043c6070bd 100644
--- a/src/Gui/SoMouseWheelEvent.h
+++ b/src/Gui/SoMouseWheelEvent.h
@@ -29,6 +29,7 @@
 //#endif
 
 #include <Inventor/events/SoEvent.h>
+#include <Inventor/events/SoSubEvent.h>
 
 /**
  * @brief The SoMouseWheelEvent class is a temporary replacement for