diff --git a/builtin/mainmenu/dlg_settings_advanced.lua b/builtin/mainmenu/dlg_settings_advanced.lua
index 67e8c9ede..6d40ace35 100644
--- a/builtin/mainmenu/dlg_settings_advanced.lua
+++ b/builtin/mainmenu/dlg_settings_advanced.lua
@@ -670,14 +670,18 @@ local function create_change_setting_formspec(dialogdata)
 		height = height + 1.1
 
 	elseif setting.type == "flags" then
-		local enabled_flags = flags_to_table(get_current_value(setting))
+		local current_flags = flags_to_table(get_current_value(setting))
 		local flags = {}
-		for _, name in ipairs(enabled_flags) do
+		for _, name in ipairs(current_flags) do
 			-- Index by name, to avoid iterating over all enabled_flags for every possible flag.
-			flags[name] = true
+			if name:sub(1, 2) == "no" then
+				flags[name:sub(3)] = false
+			else
+				flags[name] = true
+			end
 		end
-		local flags_count = #setting.possible
-		local max_height = flags_count / 4
+		local flags_count = #setting.possible / 2
+		local max_height = math.ceil(flags_count / 2) / 2
 
 		-- More space for flags
 		description_height = description_height - 1
@@ -685,19 +689,21 @@ local function create_change_setting_formspec(dialogdata)
 
 		local fields = {} -- To build formspec
 		for i, name in ipairs(setting.possible) do
-			local x = 0.5
-			local y = height + i / 2 - 0.75
-			if i - 1 >= flags_count / 2 then -- 2nd column
-				x = 5
-				y = y - max_height
-			end
-			local checkbox_name = "cb_" .. name
-			local is_enabled = flags[name] == true -- to get false if nil
-			checkboxes[checkbox_name] = is_enabled
+			if name:sub(1, 2) ~= "no" then
+				local x = 0.5
+				local y = height + i / 2 - 0.75
+				if i - 1 >= flags_count / 2 then -- 2nd column
+					x = 5
+					y = y - max_height
+				end
+				local checkbox_name = "cb_" .. name
+				local is_enabled = flags[name] == true -- to get false if nil
+				checkboxes[checkbox_name] = is_enabled
 
-			fields[#fields + 1] = ("checkbox[%f,%f;%s;%s;%s]"):format(
-				x, y, checkbox_name, name, tostring(is_enabled)
-			)
+				fields[#fields + 1] = ("checkbox[%f,%f;%s;%s;%s]"):format(
+					x, y, checkbox_name, name, tostring(is_enabled)
+				)
+			end
 		end
 		formspec = table.concat(fields)
 		height = height + max_height + 0.25
@@ -833,8 +839,12 @@ local function handle_change_setting_buttons(this, fields)
 		elseif setting.type == "flags" then
 			local values = {}
 			for _, name in ipairs(setting.possible) do
-				if checkboxes["cb_" .. name] then
-					table.insert(values, name)
+				if name:sub(1, 2) ~= "no" then
+					if checkboxes["cb_" .. name] then
+						table.insert(values, name)
+					else
+						table.insert(values, "no" .. name)
+					end
 				end
 			end
 
diff --git a/builtin/settingtypes.txt b/builtin/settingtypes.txt
index a3059a7cb..4254603e2 100644
--- a/builtin/settingtypes.txt
+++ b/builtin/settingtypes.txt
@@ -1887,7 +1887,7 @@ mgfractal_np_dungeons (Dungeon noise) noise_params_3d 0.9, 0.5, (500, 500, 500),
 #    'vary_river_depth': If enabled, low humidity and high heat causes rivers
 #    to become shallower and occasionally dry.
 #    'altitude_dry': Reduces humidity with altitude.
-mgvalleys_spflags (Mapgen Valleys specific flags) flags altitude_chill,humid_rivers,vary_river_depth,altitude_dry altitude_chill,noaltitude_chill,humid_rivers,nohumid_rivers,vary_river_depth,novary_river_depth,altitude_dry,noaltitude_dry
+mgvalleys_spflags (Mapgen Valleys specific flags) flags altitude_chill,humid_rivers,vary_river_depth,altitude_dry altitude_chill,humid_rivers,vary_river_depth,altitude_dry,noaltitude_chill,nohumid_rivers,novary_river_depth,noaltitude_dry
 
 #    The vertical distance over which heat drops by 20 if 'altitude_chill' is
 #    enabled. Also the vertical distance over which humidity drops by 10 if
diff --git a/src/defaultsettings.cpp b/src/defaultsettings.cpp
index b6ab7c9a0..7756bc45d 100644
--- a/src/defaultsettings.cpp
+++ b/src/defaultsettings.cpp
@@ -417,7 +417,7 @@ void set_default_settings(Settings *settings)
 	settings->setDefault("water_level", "1");
 	settings->setDefault("mapgen_limit", "31000");
 	settings->setDefault("chunksize", "5");
-	settings->setDefault("mg_flags", "dungeons");
+	settings->setDefault("mg_flags", "caves,dungeons,light,decorations,biomes");
 	settings->setDefault("fixed_map_seed", "");
 	settings->setDefault("max_block_generate_distance", "8");
 	settings->setDefault("projecting_dungeons", "true");