script.on_event(defines.events.on_player_setup_blueprint, function(event)
	local player = game.get_player(event.player_index)
	if not player then
		return
	end

	-- Find bp
	local bp = nil
	if event.record then
		bp = event.record.get_selected_record(player)
	elseif event.stack then
    local stack = event.stack
		while stack and stack.is_blueprint_book do
			stack = stack.get_inventory(defines.inventory.item_main)[stack.active_index]
		end
		if stack and stack.is_blueprint then
			bp = stack
		end
	end
	if not bp then
		return
	end

	-- Set entities to the result of get_entities. This should make no
	-- change to the bp.
	local entities = bp.get_blueprint_entities() or {}
	bp.set_blueprint_entities(entities)
end)