diff --git a/worktable.lua b/worktable.lua
index 609b08d..b1e9df2 100644
--- a/worktable.lua
+++ b/worktable.lua
@@ -63,23 +63,18 @@ local function xfields(pos, formname, fields, sender)
 	local shape, get = {}, {}
 	local anz = 0
 
-	for m=1, #material do
-	for n=1, #def do
-		local v = material[m]
-		local w = def[n]
-
-		if (inputstack:get_name() == "default:"..v) and
-				(outputstack:get_count() < 99) and fields[w[1]] then
-			shape = "xdecor:"..w[1].."_"..v
-			anz = w[2]
+	for _, d in pairs(def) do
+		local nb, anz = d[1], d[2]
+		if outputstack:get_count() < 99 and fields[nb] then
+			shape = "xdecor:"..nb.."_"..string.sub(inputstack:get_name(), 9)
 			get = shape.." "..anz
 
+			if not minetest.registered_nodes[shape] then return end
 			inv:add_item("output", get)
 			inputstack:take_item()
 			inv:set_stack("input", 1, inputstack)
 		end
 	end
-	end
 end
 
 local function xdig(pos, player)