diff --git a/mods/CORE/mcl_init/init.lua b/mods/CORE/mcl_init/init.lua
index 6c2a414e2..7fc13dcfe 100644
--- a/mods/CORE/mcl_init/init.lua
+++ b/mods/CORE/mcl_init/init.lua
@@ -17,6 +17,9 @@ if mg_name ~= "flat" then
 else
 	-- 1 perfectly flat bedrock layer
 	local ground = minetest.get_mapgen_setting("mgflat_ground_level")
+	if not ground then
+		ground = 8
+	end
 	mcl_vars.bedrock_overworld_min = ground - 3
 	mcl_vars.bedrock_overworld_max = mcl_vars.bedrock_overworld_min
 	mcl_vars.bedrock_is_rough = false
diff --git a/mods/MAPGEN/mcl_mapgen_core/init.lua b/mods/MAPGEN/mcl_mapgen_core/init.lua
index 1c09a001b..1c7d19c35 100644
--- a/mods/MAPGEN/mcl_mapgen_core/init.lua
+++ b/mods/MAPGEN/mcl_mapgen_core/init.lua
@@ -345,11 +345,6 @@ local function register_mgv6_decorations()
 
 end
 
-local mg_name = minetest.get_mapgen_setting("mg_name")
-if mg_name == "v6" then
-	register_mgv6_decorations()
-end
-
 minetest.register_on_generated(function(minp, maxp, seed)
 	if maxp.y >= 2 and minp.y <= 0 then
 		-- Generate clay
@@ -531,3 +526,13 @@ minetest.register_on_generated(function(minp, maxp)
 	end
 end)
 
+-- Apply mapgen-specific mapgen code
+local mg_name = minetest.get_mapgen_setting("mg_name")
+if mg_name == "v6" then
+	register_mgv6_decorations()
+end
+if mg_name == "flat" then
+	minetest.set_mapgen_setting("mg_flags", "nocaves,nodungeons,nodecorations")
+else
+	minetest.set_mapgen_setting("mg_flags", "nodungeons")
+end