diff --git a/LEGO1/lego/legoomni/include/registrationbook.h b/LEGO1/lego/legoomni/include/registrationbook.h
index b6e60ae0..c49d6bec 100644
--- a/LEGO1/lego/legoomni/include/registrationbook.h
+++ b/LEGO1/lego/legoomni/include/registrationbook.h
@@ -1,6 +1,7 @@
 #ifndef REGISTRATIONBOOK_H
 #define REGISTRATIONBOOK_H
 
+#include "legogamestate.h"
 #include "legoworld.h"
 
 class InfocenterState;