diff --git a/builtin/settingtypes.txt b/builtin/settingtypes.txt
index 8ac6ab6da..25849e0c7 100644
--- a/builtin/settingtypes.txt
+++ b/builtin/settingtypes.txt
@@ -829,10 +829,10 @@ max_block_generate_distance (Max block generate distance) int 6
 map_generation_limit (Map generation limit) int 31000 0 31000
 
 #    Global map generation attributes.
+#    The 'trees' flag only has effect in mgv6.
 #    Flags that are not specified in the flag string are not modified from the default.
 #    Flags starting with "no" are used to explicitly disable them.
-#    'trees' and 'flat' flags only have effect in mgv6.
-mg_flags (Mapgen flags) flags trees,caves,dungeons,light trees,caves,dungeons,light,flat,notrees,nocaves,nodungeons,nolight,noflat
+mg_flags (Mapgen flags) flags trees,caves,dungeons,light trees,caves,dungeons,light,notrees,nocaves,nodungeons,nolight
 
 [**Advanced]
 
@@ -889,7 +889,7 @@ mgv5_np_cave2 (Mapgen v5 cave2 noise parameters) noise_params 0, 12, (50, 50, 50
 #    When snowbiomes are enabled jungles are enabled and the jungles flag is ignored.
 #    Flags that are not specified in the flag string are not modified from the default.
 #    Flags starting with "no" are used to explicitly disable them.
-mgv6_spflags (Mapgen v6 flags) flags jungles,biomeblend,mudflow,snowbiomes jungles,biomeblend,mudflow,snowbiomes,nojungles,nobiomeblend,nomudflow,nosnowbiomes
+mgv6_spflags (Mapgen v6 flags) flags jungles,biomeblend,mudflow,snowbiomes jungles,biomeblend,mudflow,snowbiomes,flat,nojungles,nobiomeblend,nomudflow,nosnowbiomes,noflat
 
 #    Controls size of deserts and beaches in Mapgen v6.
 #    When snowbiomes are enabled 'mgv6_freq_desert' is ignored.
diff --git a/minetest.conf.example b/minetest.conf.example
index 10b090beb..e5adc0e1d 100644
--- a/minetest.conf.example
+++ b/minetest.conf.example
@@ -1021,10 +1021,10 @@
 # map_generation_limit = 31000
 
 #    Global map generation attributes.
+#    The 'trees' flag only has effect in mgv6.
 #    Flags that are not specified in the flag string are not modified from the default.
 #    Flags starting with "no" are used to explicitly disable them.
-#    'trees' and 'flat' flags only have effect in mgv6.
-#    type: flags possible values: trees, caves, dungeons, light, flat, notrees, nocaves, nodungeons, nolight, noflat
+#    type: flags possible values: trees, caves, dungeons, light, notrees, nocaves, nodungeons, nolight
 # mg_flags = trees,caves,dungeons,light
 
 ### Advanced
@@ -1093,7 +1093,7 @@
 #    When snowbiomes are enabled jungles are enabled and the jungles flag is ignored.
 #    Flags that are not specified in the flag string are not modified from the default.
 #    Flags starting with "no" are used to explicitly disable them.
-#    type: flags possible values: jungles, biomeblend, mudflow, snowbiomes, nojungles, nobiomeblend, nomudflow, nosnowbiomes
+#    type: flags possible values: jungles, biomeblend, mudflow, snowbiomes, flat, nojungles, nobiomeblend, nomudflow, nosnowbiomes, noflat
 # mgv6_spflags = jungles,biomeblend,mudflow,snowbiomes
 
 #    Controls size of deserts and beaches in Mapgen v6.
diff --git a/src/mapgen_v6.cpp b/src/mapgen_v6.cpp
index 82ed6c4d4..3f3ccba4f 100644
--- a/src/mapgen_v6.cpp
+++ b/src/mapgen_v6.cpp
@@ -42,6 +42,7 @@ FlagDesc flagdesc_mapgen_v6[] = {
 	{"biomeblend", MGV6_BIOMEBLEND},
 	{"mudflow",    MGV6_MUDFLOW},
 	{"snowbiomes", MGV6_SNOWBIOMES},
+	{"flat",       MGV6_FLAT},
 	{NULL,         0}
 };
 
@@ -263,7 +264,7 @@ float MapgenV6::baseTerrainLevel(float terrain_base, float terrain_higher,
 
 float MapgenV6::baseTerrainLevelFromNoise(v2s16 p)
 {
-	if (flags & MG_FLAT)
+	if ((spflags & MGV6_FLAT) || (flags & MG_FLAT))
 		return water_level;
 
 	float terrain_base   = NoisePerlin2D_PO(&noise_terrain_base->np,
@@ -289,7 +290,7 @@ float MapgenV6::baseTerrainLevelFromMap(v2s16 p)
 
 float MapgenV6::baseTerrainLevelFromMap(int index)
 {
-	if (flags & MG_FLAT)
+	if ((spflags & MGV6_FLAT) || (flags & MG_FLAT))
 		return water_level;
 
 	float terrain_base   = noise_terrain_base->result[index];
@@ -386,7 +387,7 @@ bool MapgenV6::getHaveAppleTree(v2s16 p)
 
 float MapgenV6::getMudAmount(int index)
 {
-	if (flags & MG_FLAT)
+	if ((spflags & MGV6_FLAT) || (flags & MG_FLAT))
 		return MGV6_AVERAGE_MUD_AMOUNT;
 
 	/*return ((float)AVERAGE_MUD_AMOUNT + 2.0 * noise2d_perlin(
@@ -603,7 +604,7 @@ void MapgenV6::calculateNoise()
 	int fx = full_node_min.X;
 	int fz = full_node_min.Z;
 
-	if (!(flags & MG_FLAT)) {
+	if (!((spflags & MGV6_FLAT) || (flags & MG_FLAT))) {
 		noise_terrain_base->perlinMap2D_PO(x, 0.5, z, 0.5);
 		noise_terrain_higher->perlinMap2D_PO(x, 0.5, z, 0.5);
 		noise_steepness->perlinMap2D_PO(x, 0.5, z, 0.5);
diff --git a/src/mapgen_v6.h b/src/mapgen_v6.h
index 685fdad7e..dec92ab48 100644
--- a/src/mapgen_v6.h
+++ b/src/mapgen_v6.h
@@ -36,6 +36,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #define MGV6_BIOMEBLEND 0x02
 #define MGV6_MUDFLOW    0x04
 #define MGV6_SNOWBIOMES 0x08
+#define MGV6_FLAT       0x10
 
 
 extern FlagDesc flagdesc_mapgen_v6[];