diff --git a/LEGO1/act3actor.h b/LEGO1/act3actor.h
index cd1e1fcd..00d06495 100644
--- a/LEGO1/act3actor.h
+++ b/LEGO1/act3actor.h
@@ -1,12 +1,14 @@
 #ifndef ACT3ACTOR_H
 #define ACT3ACTOR_H
 
+#include "mxcore.h"
+
 // FIXME: Uncertain location. There are three vtables which eventually call this
 //        class' ClassName() function, but none of them call it directly.
 class Act3Actor : public MxCore {
 public:
 	// FUNCTION: LEGO1 0x100431b0
-	inline virtual const char* ClassName() override
+	inline virtual const char* ClassName() const override
 	{
 		// STRING: LEGO1 0x100f03ac
 		return "Act3Actor";