diff --git a/README.md b/README.md
index 9e1e69e..5bd5ae6 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ A recreation of Cave Game, the earliest version of Minecraft.
 
 Whilst looking like cobble, stone is infact `minecraft:stone`.
 
-Technical names `minecraft:nnn` and `nnn` are aliases to the "modern" Minecraft names.
+Block's ID are aliased to their "modern" Minecraft name.
 
 Select mapgen `singlenode` for a truly flat world.
 Mapgen v6 unsupported.
diff --git a/mods/mapgen/init.lua b/mods/mapgen/init.lua
index cdbf4ad..4992c89 100644
--- a/mods/mapgen/init.lua
+++ b/mods/mapgen/init.lua
@@ -1,5 +1,28 @@
 
-if minetest.get_mapgen_params().mgname == "singlenode" then
+local mgparams = minetest.get_mapgen_params()
+if mgparams.mgname == "v6" then
+	error("Mapgen 'v6' is not supported by Cave Game.", 0)
+end
+
+minetest.register_alias("mapgen_stone", "minecraft:stone")
+minetest.register_alias("mapgen_water_source", "air")
+minetest.register_alias("mapgen_river_water_source", "air")
+
+
+-- FIXME: Why dosen't node_top work properly?
+minetest.register_biome({
+	name = "cavegame",
+	node_dust = "minecraft:grass",
+--	node_top = "minecraft:grass",
+--	depth_top = 1,
+	node_stone = "minecraft:stone",
+	heat_point = 50,
+	humidity_point = 50,
+	y_min = -3100, y_max = 3100,
+})
+
+
+if mgparams.mgname == "singlenode" then
 	local ground_level = tonumber(minetest.settings:get("water_level") or 1)
 	local air = minetest.get_content_id("air")
 	local stone = minetest.get_content_id("minecraft:stone")
@@ -39,16 +62,4 @@ if minetest.get_mapgen_params().mgname == "singlenode" then
 			return true
 		end)
 	end
-else
-	-- FIXME: Why dosen't node_top work properly?
-	minetest.register_biome({
-		name = "cavegame",
-		node_dust = "minecraft:grass",
-	--	node_top = "minecraft:grass",
-	--	depth_top = 1,
-		node_stone = "minecraft:stone",
-		heat_point = 50,
-		humidity_point = 50,
-		y_min = -3100, y_max = 3100,
-	})
 end
diff --git a/mods/nodes/init.lua b/mods/nodes/init.lua
index d2f8d0b..a3c7133 100644
--- a/mods/nodes/init.lua
+++ b/mods/nodes/init.lua
@@ -1,11 +1,16 @@
 
-minetest.register_alias("mapgen_stone", "minecraft:stone")
-minetest.register_alias("mapgen_water_source", "air")
-minetest.register_alias("mapgen_river_water_source", "air")
+minetest.register_on_mods_loaded(function()
+	for name,def in pairs(minetest.registered_nodes) do
+		if def.order then
+			minetest.register_alias(tostring(def.order), name)
+		end
+	end
+end)
 
 
-minetest.register_alias("1", "minecraft:stone")
-minetest.register_alias("minecraft:1", "minecraft:stone")
+
+ -- nodes --
+
 minetest.register_node(":minecraft:stone", {
 	order = 1,
 	description = "Stone",
@@ -14,8 +19,6 @@ minetest.register_node(":minecraft:stone", {
 	is_ground_content = true,
 })
 
-minetest.register_alias("2", "minecraft:grass")
-minetest.register_alias("minecraft:2", "minecraft:grass")
 minetest.register_node(":minecraft:grass", {
 	order = 2,
 	description = "Grass",