diff --git a/init.lua b/init.lua
index 83dd290..883aa1f 100644
--- a/init.lua
+++ b/init.lua
@@ -499,11 +499,16 @@ end
 function visible_items(data)
 	local ret = {}
 	for item,_ in pairs(data.held_items) do
-		table.insert(ret, item)
+		if _ and item ~= "" then
+			table.insert(ret, item)
+		end
 	end
 	for item,_ in pairs(data.known_items) do
-		table.insert(ret, item)
+		if _ and item ~= "" then
+			table.insert(ret, item)
+		end
 	end
+	table.sort(ret)
 	return ret
 end
 
@@ -529,8 +534,11 @@ function update_known_items(player, item_name)
 		-- Mark items craftable with this (and other) items as known.
 		local new_recipes = 0
 		for _,out_item_name in pairs(known_crafting_outputs(data, item_name)) do
-			new_recipes = new_recipes + 1
 			data.known_items[out_item_name] = true
+			if show_item(minetest.registered_items[out_item_name]) then
+				new_recipes = new_recipes + 1
+				data.known_items[out_item_name] = true
+			end
 		end
 
 		-- Reset item-list.