diff --git a/builtin/misc_register.lua b/builtin/misc_register.lua
index 4041fb9e2..2d25568b6 100644
--- a/builtin/misc_register.lua
+++ b/builtin/misc_register.lua
@@ -307,6 +307,7 @@ end
 
 minetest.registered_on_chat_messages, minetest.register_on_chat_message = make_registration()
 minetest.registered_globalsteps, minetest.register_globalstep = make_registration()
+minetest.registered_on_mapgen_inits, minetest.register_on_mapgen_init = make_registration()
 minetest.registered_on_shutdown, minetest.register_on_shutdown = make_registration()
 minetest.registered_on_punchnodes, minetest.register_on_punchnode = make_registration()
 minetest.registered_on_placenodes, minetest.register_on_placenode = make_registration()
diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 62abb2e3e..a4e1372da 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -1034,6 +1034,9 @@ minetest.register_on_player_receive_fields(func(player, formname, fields))
 ^ Called when a button is pressed in player's inventory form
 ^ Newest functions are called first
 ^ If function returns true, remaining functions are not called
+minetest.register_on_mapgen_init(func(MapgenParams))
+^ Called just before the map generator is initialized but before the environment is initialized
+^ MapgenParams consists of a table with the fields mgname, seed, water_level, and flags
 
 Other registration functions:
 minetest.register_chatcommand(cmd, chatcommand definition)
@@ -1118,6 +1121,14 @@ minetest.get_voxel_manip()
 ^ Return voxel manipulator object
 minetest.get_mapgen_object(objectname)
 ^ Return requested mapgen object if available (see Mapgen objects)
+minetest.set_mapgen_params(MapgenParams)
+^ Set map generation parameters
+^ Function can *only* be called within a minetest.on_mapgen_init() callback
+^ Takes a table as an argument with the fields mgname, seed, water_level, flags, and flagmask.
+^ Leave field unset to leave that parameter unchanged
+^ flagmask field must be set to all mapgen flags that are being modified
+^ flags contains only the flags that are being set
+^ flags and flagmask are in the same format and have the same options as 'mgflags' in minetest.conf
 minetest.clear_objects()
 ^ clear all objects in the environments
 minetest.line_of_sight(pos1,pos2,stepsize) ->true/false
diff --git a/minetest.conf.example b/minetest.conf.example
index 07063b913..3f1977268 100644
--- a/minetest.conf.example
+++ b/minetest.conf.example
@@ -331,7 +331,7 @@
 #water_level = 1
 # Size of chunks to be generated.
 #chunksize = 5
-# Map generation attributes.  Currently supported: trees, caves, flat, v6_biome_blend, v6_jungles, dungeons
+# Map generation attributes.  Currently supported: trees, caves, flat, v6_biome_blend, v6_jungles, dungeons, nolight
 #mg_flags = trees, caves, v6_biome_blend
 # How large deserts and beaches are
 #mgv6_freq_desert = 0.45
diff --git a/src/emerge.cpp b/src/emerge.cpp
index e1e6c6574..09a58149d 100644
--- a/src/emerge.cpp
+++ b/src/emerge.cpp
@@ -59,6 +59,10 @@ EmergeManager::EmergeManager(IGameDef *gamedef) {
 	this->biomedef = new BiomeDefManager();
 	this->params   = NULL;
 	
+	this->luaoverride_params = NULL;
+	this->luaoverride_params_modified = 0;
+	this->luaoverride_flagmask = 0;
+	
 	mapgen_debug_info = g_settings->getBool("enable_mapgen_debug_info");
 
 	queuemutex.Init();
@@ -124,12 +128,37 @@ void EmergeManager::initMapgens(MapgenParams *mgparams) {
 	if (mapgen.size())
 		return;
 	
+	// Resolve names of nodes for things that were registered
+	// (at this point, the registration period is over)
 	biomedef->resolveNodeNames(ndef);
+	
 	for (size_t i = 0; i != ores.size(); i++)
 		ores[i]->resolveNodeNames(ndef);
+		
 	for (size_t i = 0; i != decorations.size(); i++)
 		decorations[i]->resolveNodeNames(ndef);
 	
+	// Apply mapgen parameter overrides from Lua
+	if (luaoverride_params) {
+		if (luaoverride_params_modified & MGPARAMS_SET_MGNAME)
+			mgparams->mg_name = luaoverride_params->mg_name;
+		
+		if (luaoverride_params_modified & MGPARAMS_SET_SEED)
+			mgparams->seed = luaoverride_params->seed;
+		
+		if (luaoverride_params_modified & MGPARAMS_SET_WATER_LEVEL)
+			mgparams->water_level = luaoverride_params->water_level;
+		
+		if (luaoverride_params_modified & MGPARAMS_SET_FLAGS) {
+			mgparams->flags &= ~luaoverride_flagmask;
+			mgparams->flags |= luaoverride_params->flags;
+		}
+		
+		delete luaoverride_params;
+		luaoverride_params = NULL;
+	}
+	
+	// Create the mapgens
 	this->params = mgparams;
 	for (size_t i = 0; i != emergethread.size(); i++) {
 		mg = createMapgen(params->mg_name, 0, params);
diff --git a/src/emerge.h b/src/emerge.h
index d51177110..ee95c348f 100644
--- a/src/emerge.h
+++ b/src/emerge.h
@@ -24,6 +24,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <queue>
 #include "util/thread.h"
 
+#define MGPARAMS_SET_MGNAME      1
+#define MGPARAMS_SET_SEED        2
+#define MGPARAMS_SET_WATER_LEVEL 4
+#define MGPARAMS_SET_FLAGS       8
+
 #define BLOCK_EMERGE_ALLOWGEN (1<<0)
 
 #define EMERGE_DBG_OUT(x) \
@@ -79,6 +84,10 @@ public:
 	u16 qlimit_diskonly;
 	u16 qlimit_generate;
 	
+	MapgenParams *luaoverride_params;
+	u32 luaoverride_params_modified;
+	u32 luaoverride_flagmask;
+	
 	//block emerge queue data structures
 	JMutex queuemutex;
 	std::map<v3s16, BlockEmergeData *> blocks_enqueued;
diff --git a/src/mapgen.cpp b/src/mapgen.cpp
index d1a38bb20..d80d2107f 100644
--- a/src/mapgen.cpp
+++ b/src/mapgen.cpp
@@ -44,6 +44,7 @@ FlagDesc flagdesc_mapgen[] = {
 	{"v6_jungles",     MGV6_JUNGLES},
 	{"v6_biome_blend", MGV6_BIOME_BLEND},
 	{"flat",           MG_FLAT},
+	{"nolight",        MG_NOLIGHT},
 	{NULL,             0}
 };
 
diff --git a/src/mapgen.h b/src/mapgen.h
index 96a27ade7..9a8b99c4a 100644
--- a/src/mapgen.h
+++ b/src/mapgen.h
@@ -35,6 +35,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #define MGV6_JUNGLES     0x08
 #define MGV6_BIOME_BLEND 0x10
 #define MG_FLAT          0x20
+#define MG_NOLIGHT       0x40
 
 /////////////////// Ore generation flags
 // Use absolute value of height to determine ore placement
@@ -80,8 +81,8 @@ struct MapgenParams {
 		flags       = MG_TREES | MG_CAVES | MGV6_BIOME_BLEND;
 	}
 	
-	virtual bool readParams(Settings *settings) = 0;
-	virtual void writeParams(Settings *settings) = 0;
+	virtual bool readParams(Settings *settings) { return true; }
+	virtual void writeParams(Settings *settings) {}
 	virtual ~MapgenParams() {}
 };
 
diff --git a/src/mapgen_math.cpp b/src/mapgen_math.cpp
index a8a093a4a..6d0bf1292 100644
--- a/src/mapgen_math.cpp
+++ b/src/mapgen_math.cpp
@@ -171,8 +171,8 @@ void MapgenMathParams::writeParams(Settings *settings) {
 
 MapgenMath::MapgenMath(int mapgenid, MapgenMathParams *params_, EmergeManager *emerge) : MapgenV7(mapgenid, params_, emerge) {
 	mg_params = params_;
-	this->lighting = 0;
-	this->ridges   = 0;
+	this->flags |= MG_NOLIGHT;
+	this->ridges = 0;
 
 	Json::Value & params = mg_params->params;
 	invert = params["invert"].empty() ? 1 : params["invert"].asBool(); //params["invert"].empty()?1:params["invert"].asBool();
diff --git a/src/mapgen_singlenode.cpp b/src/mapgen_singlenode.cpp
index f05ddd2f4..30787c6bb 100644
--- a/src/mapgen_singlenode.cpp
+++ b/src/mapgen_singlenode.cpp
@@ -42,6 +42,7 @@ void MapgenSinglenodeParams::writeParams(Settings *settings) {
 ///////////////////////////////////////////////////////////////////////////////
 
 MapgenSinglenode::MapgenSinglenode(int mapgenid, MapgenSinglenodeParams *params) {
+	flags = params->flags;
 }
 
 
@@ -91,8 +92,9 @@ void MapgenSinglenode::makeChunk(BlockMakeData *data) {
 	updateLiquid(&data->transforming_liquid, node_min, node_max);
 
 	// Calculate lighting
-	calcLighting(node_min - v3s16(1, 0, 1) * MAP_BLOCKSIZE,
-				 node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE);
+	if (!(flags & MG_NOLIGHT))
+		calcLighting(node_min - v3s16(1, 0, 1) * MAP_BLOCKSIZE,
+					 node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE);
 	
 	this->generating = false;
 }
diff --git a/src/mapgen_singlenode.h b/src/mapgen_singlenode.h
index 8b816aa25..e2eb1bb90 100644
--- a/src/mapgen_singlenode.h
+++ b/src/mapgen_singlenode.h
@@ -33,6 +33,8 @@ struct MapgenSinglenodeParams : public MapgenParams {
 
 class MapgenSinglenode : public Mapgen {
 public:
+	u32 flags;
+
 	MapgenSinglenode(int mapgenid, MapgenSinglenodeParams *params);
 	~MapgenSinglenode();
 	
diff --git a/src/mapgen_v6.cpp b/src/mapgen_v6.cpp
index d3db00dc2..7643f3a48 100644
--- a/src/mapgen_v6.cpp
+++ b/src/mapgen_v6.cpp
@@ -459,8 +459,9 @@ void MapgenV6::makeChunk(BlockMakeData *data) {
 	}
 
 	// Calculate lighting
-	calcLighting(node_min - v3s16(1, 1, 1) * MAP_BLOCKSIZE,
-				 node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE);
+	if (!(flags & MG_NOLIGHT))
+		calcLighting(node_min - v3s16(1, 1, 1) * MAP_BLOCKSIZE,
+					 node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE);
 	
 	this->generating = false;
 }
diff --git a/src/mapgen_v7.cpp b/src/mapgen_v7.cpp
index 870e7343e..861cdde62 100644
--- a/src/mapgen_v7.cpp
+++ b/src/mapgen_v7.cpp
@@ -77,7 +77,6 @@ MapgenV7::MapgenV7(int mapgenid, MapgenV7Params *params, EmergeManager *emerge)
 	this->seed     = (int)params->seed;
 	this->water_level = params->water_level;
 	this->flags    = params->flags;
-	this->lighting = 1;
 	this->ridges   = 1;
 
 	this->csize   = v3s16(1, 1, 1) * params->chunksize * MAP_BLOCKSIZE;
@@ -215,9 +214,9 @@ void MapgenV7::makeChunk(BlockMakeData *data) {
 	
 	updateLiquid(&data->transforming_liquid, full_node_min, full_node_max);
 	
-	if (this->lighting)
+	if (!(flags & MG_NOLIGHT))
 		calcLighting(node_min - v3s16(1, 0, 1) * MAP_BLOCKSIZE,
-				 node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE);
+					 node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE);
 	//setLighting(node_min - v3s16(1, 0, 1) * MAP_BLOCKSIZE,
 	//			node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE, 0xFF);
 
diff --git a/src/mapgen_v7.h b/src/mapgen_v7.h
index 6267350d6..e39bf7158 100644
--- a/src/mapgen_v7.h
+++ b/src/mapgen_v7.h
@@ -59,7 +59,6 @@ public:
 
 	int ystride;
 	u32 flags;
-	bool lighting;
 	bool ridges;
 
 	u32 blockseed;
diff --git a/src/script/cpp_api/s_env.cpp b/src/script/cpp_api/s_env.cpp
index 334d196bc..632b28f45 100644
--- a/src/script/cpp_api/s_env.cpp
+++ b/src/script/cpp_api/s_env.cpp
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "common/c_converter.h"
 #include "log.h"
 #include "environment.h"
+#include "mapgen.h"
 #include "lua_api/l_env.h"
 
 extern "C" {
@@ -55,6 +56,33 @@ void ScriptApiEnv::environment_Step(float dtime)
 	runCallbacks(1, RUN_CALLBACKS_MODE_FIRST);
 }
 
+void ScriptApiEnv::environment_OnMapgenInit(MapgenParams *mgparams)
+{
+	SCRIPTAPI_PRECHECKHEADER
+	
+	// Get minetest.registered_on_mapgen_inits
+	lua_getglobal(L, "minetest");
+	lua_getfield(L, -1, "registered_on_mapgen_inits");
+
+	// Call callbacks
+	lua_newtable(L);
+	
+	lua_pushstring(L, mgparams->mg_name.c_str());
+	lua_setfield(L, -2, "mgname");
+	
+	lua_pushinteger(L, mgparams->seed);
+	lua_setfield(L, -2, "seed");
+	
+	lua_pushinteger(L, mgparams->water_level);
+	lua_setfield(L, -2, "water_level");
+	
+	std::string flagstr = writeFlagString(mgparams->flags, flagdesc_mapgen);
+	lua_pushstring(L, flagstr.c_str());
+	lua_setfield(L, -2, "flags");
+	
+	runCallbacks(1, RUN_CALLBACKS_MODE_FIRST);
+}
+
 void ScriptApiEnv::initializeEnvironment(ServerEnvironment *env)
 {
 	SCRIPTAPI_PRECHECKHEADER
diff --git a/src/script/cpp_api/s_env.h b/src/script/cpp_api/s_env.h
index c5b739eb4..51cf15036 100644
--- a/src/script/cpp_api/s_env.h
+++ b/src/script/cpp_api/s_env.h
@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "irr_v3d.h"
 
 class ServerEnvironment;
+struct MapgenParams;
 
 class ScriptApiEnv
 		: virtual public ScriptApiBase
@@ -33,6 +34,8 @@ public:
 	void environment_Step(float dtime);
 	// After generating a piece of map
 	void environment_OnGenerated(v3s16 minp, v3s16 maxp,u32 blockseed);
+	// After initializing mapgens
+	void environment_OnMapgenInit(MapgenParams *mgparams);
 
 	void initializeEnvironment(ServerEnvironment *env);
 };
diff --git a/src/script/lua_api/l_env.cpp b/src/script/lua_api/l_env.cpp
index b5c40977e..b6bafbcd9 100644
--- a/src/script/lua_api/l_env.cpp
+++ b/src/script/lua_api/l_env.cpp
@@ -652,6 +652,59 @@ int ModApiEnvMod::l_get_mapgen_object(lua_State *L)
 	return nargs;
 }
 
+// minetest.set_mapgen_params(params)
+// set mapgen parameters
+int ModApiEnvMod::l_set_mapgen_params(lua_State *L)
+{
+	if (!lua_istable(L, 1))
+		return 0;
+
+	EmergeManager *emerge = getServer(L)->getEmergeManager();
+	if (emerge->mapgen.size())
+		return 0;
+	
+	MapgenParams *oparams = new MapgenParams;
+	u32 paramsmodified = 0;
+	u32 flagmask = 0;
+	
+	lua_getfield(L, 1, "mgname");
+	if (lua_isstring(L, -1)) {
+		oparams->mg_name = std::string(lua_tostring(L, -1));
+		paramsmodified |= MGPARAMS_SET_MGNAME;
+	}
+	
+	lua_getfield(L, 1, "seed");
+	if (lua_isnumber(L, -1)) {
+		oparams->seed = lua_tointeger(L, -1);
+		paramsmodified |= MGPARAMS_SET_SEED;
+	}
+	
+	lua_getfield(L, 1, "water_level");
+	if (lua_isnumber(L, -1)) {
+		oparams->water_level = lua_tointeger(L, -1);
+		paramsmodified |= MGPARAMS_SET_WATER_LEVEL;
+	}
+
+	lua_getfield(L, 1, "flags");
+	if (lua_isstring(L, -1)) {
+		std::string flagstr = std::string(lua_tostring(L, -1));
+		oparams->flags = readFlagString(flagstr, flagdesc_mapgen);
+		paramsmodified |= MGPARAMS_SET_FLAGS;
+	
+		lua_getfield(L, 1, "flagmask");
+		if (lua_isstring(L, -1)) {
+			flagstr = std::string(lua_tostring(L, -1));
+			flagmask = readFlagString(flagstr, flagdesc_mapgen);
+		}
+	}
+	
+	emerge->luaoverride_params          = oparams;
+	emerge->luaoverride_params_modified = paramsmodified;
+	emerge->luaoverride_flagmask        = flagmask;
+	
+	return 0;
+}
+
 // minetest.clear_objects()
 // clear all objects in the environment
 int ModApiEnvMod::l_clear_objects(lua_State *L)
@@ -799,6 +852,7 @@ bool ModApiEnvMod::Initialize(lua_State *L,int top)
 	retval &= API_FCT(get_perlin_map);
 	retval &= API_FCT(get_voxel_manip);
 	retval &= API_FCT(get_mapgen_object);
+	retval &= API_FCT(set_mapgen_params);
 	retval &= API_FCT(clear_objects);
 	retval &= API_FCT(spawn_tree);
 	retval &= API_FCT(find_path);
diff --git a/src/script/lua_api/l_env.h b/src/script/lua_api/l_env.h
index 8f769e350..713cfa69f 100644
--- a/src/script/lua_api/l_env.h
+++ b/src/script/lua_api/l_env.h
@@ -117,6 +117,10 @@ private:
 	// minetest.get_mapgen_object(objectname)
 	// returns the requested object used during map generation
 	static int l_get_mapgen_object(lua_State *L);
+	
+	// minetest.set_mapgen_params(params)
+	// set mapgen parameters
+	static int l_set_mapgen_params(lua_State *L);
 
 	// minetest.clear_objects()
 	// clear all objects in the environment
diff --git a/src/server.cpp b/src/server.cpp
index 016922103..1618a0915 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -807,7 +807,12 @@ Server::Server(
 	ServerMap *servermap = new ServerMap(path_world, this, m_emerge);
 	m_env = new ServerEnvironment(servermap, m_script, this, this);
 	
-	m_emerge->initMapgens(servermap->getMapgenParams());
+	// Run some callbacks after the MG params have been set up but before activation
+	MapgenParams *mgparams = servermap->getMapgenParams();
+	m_script->environment_OnMapgenInit(mgparams);
+	
+	// Initialize mapgens
+	m_emerge->initMapgens(mgparams);
 
 	// Give environment reference to scripting api
 	m_script->initializeEnvironment(m_env);