diff --git a/technic/machines/register/common.lua b/technic/machines/register/common.lua
index 51747d8..6d4c066 100644
--- a/technic/machines/register/common.lua
+++ b/technic/machines/register/common.lua
@@ -34,12 +34,28 @@ end
 
 -- handles the machine upgrades when set or removed
 local function on_machine_upgrade(meta, stack)
-	local stack_name = stack and stack:get_name()
-	if stack_name ~= "technic:control_logic_unit"
-	and stack_name ~= "technic:battery" then
+	local stack_name = stack:get_name()
+	if stack_name == "default:chest" then
+		meta:set_int("public", 1)
+		return 1
+	elseif stack_name ~= "technic:control_logic_unit"
+	   and stack_name ~= "technic:battery" then
 		return 0
 	end
+	return 1
+end
 
+-- something is about to be removed
+local function on_machine_downgrade(meta, stack, list)
+	if stack:get_name() == "default:chest" then
+		local inv = meta:get_inventory()
+		local upg1, upg2 = inv:get_stack("upgrade1", 1), inv:get_stack("upgrade2", 1)
+
+		-- only set 0 if theres not a nother chest in the other list too
+		if (not upg1 or not upg2 or upg1:get_name() ~= upg2:get_name()) then
+			meta:set_int("public", 0)
+		end
+	end
 	return 1
 end
 
@@ -140,20 +156,25 @@ end
 
 local function inv_change(pos, player, count, from_list, to_list, stack)
 	local playername = player:get_player_name()
-	if minetest.is_protected(pos, playername) then
+	local meta = minetest.get_meta(pos);
+	local public = (meta:get_int("public") == 1)
+	local to_upgrade = to_list == "upgrade1" or to_list == "upgrade2"
+	local from_upgrade = from_list == "upgrade1" or from_list == "upgrade2"
+
+	if (not public or to_upgrade or from_upgrade) and minetest.is_protected(pos, playername) then
 		minetest.chat_send_player(playername, S("Inventory move disallowed due to protection"))
 		return 0
 	end
-	if to_list == "upgrade1" or to_list == "upgrade2" then
+	if to_upgrade then
 		-- only place a single item into it, if it's empty
-		local meta = minetest.get_meta(pos);
 		local empty = meta:get_inventory():is_empty(to_list)
 		if empty then
 			return on_machine_upgrade(meta, stack)
 		end
 		return 0
-	elseif from_list == "upgrade1" or from_list == "upgrade2" then
-		on_machine_upgrade(meta, nil)
+	elseif from_upgrade then
+		-- only called on take (not move)
+		on_machine_downgrade(meta, stack, from_list)
 	end
 	return count
 end