diff --git a/hyper.h b/hyper.h
index 9cd47dff..9139a321 100644
--- a/hyper.h
+++ b/hyper.h
@@ -2443,3 +2443,4 @@ extern eMonster passive_switch;
 bool cannotPickupItem(cell *c, bool telekinesis);
 bool canPickupItemWithMagnetism(cell *c, cell *from);
 void pickupMovedItems(cell *c);
+eMonster genRuinMonster(cell *c);