diff --git a/mods/boxes/nodes.lua b/mods/boxes/nodes.lua
index 7fbe39e..5e9cfb6 100644
--- a/mods/boxes/nodes.lua
+++ b/mods/boxes/nodes.lua
@@ -116,15 +116,16 @@ local function series_enter_choice(player, id)
 	local boxes = db.series_get_boxes(id)
 	local player_id = db.player_get_id(name)
 	local completed = db.player_get_series_boxes(player_id, id)
+	local complete = {}
+	for _, v in ipairs(completed) do
+		complete[v] = true
+	end
 	for k, box_id in pairs(boxes) do
 		local bmeta = db.box_get_meta(box_id)
 		local bname = bmeta.meta.box_name or "[unnamed]"
 		local color = "#c0c0c0"
-		for _, v in ipairs(completed) do
-			if v == box_id then
-				color = "#00ff00"
-				break
-			end
+		if complete[box_id] then
+			color = "#00ff00"
 		end
 		f = f .. color
 		f = f .. minetest.formspec_escape("[" .. box_id .. "] " .. bname)