diff --git a/include/tr/class.h b/include/tr/class.h
index ed0b075..add6419 100644
--- a/include/tr/class.h
+++ b/include/tr/class.h
@@ -138,6 +138,8 @@
 		{ __VA_ARGS__ }                    \
 	}
 
+#define TR_INSTANCE_CAST(class, name)	((class)&(_##name.data))
+
 /**
  * I initialize _ (the class's base or parent class)
  * with the identifier of that class.