diff --git a/init.lua b/init.lua
index c2f75ad..772d443 100644
--- a/init.lua
+++ b/init.lua
@@ -654,18 +654,7 @@ end
 
 mt.register_on_mods_loaded(get_init_items)
 
-local function get_fields(player, ...)
-	local args, formname, fields = {...}
-	if sfinv_only then
-		fields = args[1]
-	else
-		formname, fields = args[1], args[2]
-	end
-
-	if not sfinv_only and formname ~= "craftguide" then
-		return
-	end
-
+local function on_receive_fields(player, fields)
 	local player_name = player:get_player_name()
 	local data = player_data[player_name]
 
@@ -716,63 +705,68 @@ local function get_fields(player, ...)
 		data.iX = data.iX - (fields.size_dec and 1 or -1)
 		show_fs(player, player_name)
 
-	else for item in pairs(fields) do
-		if item:find(":") then
-			if item:sub(-4) == "_inv" then
-				item = item:sub(1,-5)
+	else
+		local item
+		for field in pairs(fields) do
+			if field:find(":") then
+				item = field
+				break
 			end
+		end
 
-			local is_fuel = get_fueltime(item) > 0
-			local recipes = get_recipes(item)
+		if not item then
+			return
+		elseif item:sub(-4) == "_inv" then
+			item = item:sub(1,-5)
+		end
+
+		local is_fuel = get_fueltime(item) > 0
+		local recipes = get_recipes(item)
+		if progressive_mode then
+			recipes = apply_progressive_filters(recipes, player)
+		end
+
+		local no_recipes = not next(recipes)
+		if no_recipes and (progressive_mode or not is_fuel) then
+			return
+		end
+
+		if item ~= data.input then
+			data.show_usage = nil
+		else
+			data.show_usage = not data.show_usage
+		end
+
+		if not progressive_mode and is_fuel and no_recipes then
+			data.show_usage = true
+		end
+
+		if data.show_usage then
+			data.usages = get_item_usages(item)
+
+			if is_fuel then
+				data.usages[#data.usages + 1] = {
+					width = 1,
+					type = "normal",
+					items = {item},
+					output = "BURN",
+				}
+			end
 
 			if progressive_mode then
-				recipes = apply_progressive_filters(recipes, player)
+				data.usages = apply_progressive_filters(data.usages, player)
 			end
 
-			local no_recipes = not next(recipes)
-			if no_recipes and (progressive_mode or not is_fuel) then
-				return
-			end
-
-			if item ~= data.input then
+			if not next(data.usages) then
 				data.show_usage = nil
-			else
-				data.show_usage = not data.show_usage
 			end
-
-			if not progressive_mode and is_fuel and no_recipes then
-				data.show_usage = true
-			end
-
-			if data.show_usage then
-				data.usages = get_item_usages(item)
-
-				if is_fuel then
-					data.usages[#data.usages + 1] = {
-						width = 1,
-						type = "normal",
-						items = {item},
-						output = "BURN",
-					}
-				end
-
-				if progressive_mode and next(data.usages) then
-					data.usages =
-						apply_progressive_filters(data.usages, player)
-				end
-
-				if not next(data.usages) then
-					data.show_usage = nil
-				end
-			end
-
-			data.input        = item
-			data.recipes_item = recipes
-			data.rnum         = 1
-
-			show_fs(player, player_name)
 		end
-	     end
+
+		data.input        = item
+		data.recipes_item = recipes
+		data.rnum         = 1
+
+		show_fs(player, player_name)
 	end
 end
 
@@ -798,11 +792,15 @@ if sfinv_only then
 		end,
 
 		on_player_receive_fields = function(self, player, context, fields)
-			get_fields(player, fields)
+			on_receive_fields(player, fields)
 		end,
 	})
 else
-	mt.register_on_player_receive_fields(get_fields)
+	mt.register_on_player_receive_fields(function(player, formname, fields)
+		if formname == "craftguide" then
+			on_receive_fields(player, fields)
+		end
+	end)
 
 	local function on_use(user)
 		local player_name = user:get_player_name()