diff --git a/mods/CORE/mcl_init/init.lua b/mods/CORE/mcl_init/init.lua
index 80233b6dc..33008df58 100644
--- a/mods/CORE/mcl_init/init.lua
+++ b/mods/CORE/mcl_init/init.lua
@@ -30,7 +30,7 @@ local minecraft_height_limit = 320
 local superflat = mg_name == "flat" and minetest.get_mapgen_setting("mcl_superflat_classic") == "true"
 local singlenode = mg_name == "singlenode"
 
-local convert_old_bedrock = minetest.settings:get_bool("convert_old_bedrock", true)
+local convert_old_bedrock = minetest.settings:get_bool("mcl_convert_old_bedrock", false)
 
 -- Calculate mapgen_edge_min/mapgen_edge_max
 mcl_vars.chunksize = math.max(1, tonumber(minetest.get_mapgen_setting("chunksize")) or 5)
@@ -268,22 +268,37 @@ function mcl_vars.get_node(p, force, us_timeout)
 end
 
 -- lbm to update from old mapgen depth to new. potentially affects a lot of nodes inducing lag.
-if convert_old_bedrock then
+-- Also it will not generate ores or bedrock pattern.
+local function register_lbms()
 	minetest.register_lbm({
-			label = "Replace bedrock from old bedrock layer and air/void below to deepslate",
-			name = ":mcl_mapgen_core:replace_old_bedrock",
-			nodenames = { "mcl_core:bedrock","mcl_core:void","mcl_core:barrier"},
-			run_at_every_load = false,
-			action = function(p)
-				if p.y >= mcl_vars.mg_overworld_min and
-					p.y <= mcl_vars.mg_overworld_min_old + 5 -- 
-				then
-					if p.y <= mcl_vars.mg_bedrock_overworld_max and p.y >= mcl_vars.mg_bedrock_overworld_min then
-						minetest.swap_node(p,{name="mcl_core:bedrock" }) --TODO: bedrock pattern
-					else
-						minetest.swap_node(p,{name="mcl_deepslate:deepslate" })
-					end
+		label = "Replace bedrock from old bedrock layer and air/void below to deepslate",
+		name = ":mcl_mapgen_core:replace_old_bedrock",
+		nodenames = { "mcl_core:bedrock" },
+		run_at_every_load = true,
+		action = function(p)
+			if p.y >= mcl_vars.mg_overworld_min_old - 1 and p.y <= mcl_vars.mg_overworld_min_old + 5 then
+				minetest.swap_node(p,{name="mcl_deepslate:deepslate"})
+			end
+			--minetest.log("bedrock")
+		end
+	})
+	minetest.register_lbm({
+		label = "Replace bedrock from old bedrock layer and air/void below to deepslate",
+		name = ":mcl_mapgen_core:replace_old_void",
+		nodenames = { "mcl_core:void" },
+		run_at_every_load = true,
+		action = function(p)
+			if p.y <= mcl_vars.mg_overworld_min_old and p.y >= mcl_vars.mg_bedrock_overworld_min then
+				if p.y <= mcl_vars.mg_bedrock_overworld_max and p.y >= mcl_vars.mg_bedrock_overworld_min then
+					minetest.swap_node(p,{name="mcl_core:bedrock" })
+				else
+					minetest.swap_node(p,{name="mcl_deepslate:deepslate"})
 				end
-			end,
+			end
+			--minetest.log("void")
+		end
 	})
 end
+if convert_old_bedrock then
+	register_lbms()
+end