diff --git a/src/lib/sim/BuildingSystem.h b/src/lib/sim/BuildingSystem.h
index 73c69ea..78b15a0 100644
--- a/src/lib/sim/BuildingSystem.h
+++ b/src/lib/sim/BuildingSystem.h
@@ -143,13 +143,6 @@ public:
     void forEachIncomingItem(
         const std::function<void(const ItemType&, QPointF)>& visit) const;
 
-    // Returns the entity id of the building or construction site whose footprint
-    // exactly coincides with the ghost (type, anchor, rot) and is of the same
-    // building type.  Returns nullopt otherwise.
-    std::optional<BuildingId> findRotateInPlaceTarget(BuildingType type,
-                                                     QPoint anchor,
-                                                     Rotation rot) const;
-
     // Rotate an existing building or construction site to newRotation in place.
     // For belt-type operational buildings, re-registers with BeltSystem (items
     // currently on the tile are discarded by BeltSystem::removeTile).