diff --git a/polygons.lua b/polygons.lua
index f084961..b91a70e 100644
--- a/polygons.lua
+++ b/polygons.lua
@@ -11,8 +11,8 @@ dofile(modpath .. 'load.lua')
 
 mapgen_rivers.grid = {}
 
-local X = 1000
-local Z = 1000
+local X = mapgen_rivers.settings.grid_x_size
+local Z = mapgen_rivers.settings.grid_z_size
 
 local function offset_converter(o)
 	return (o + 0.5) * (1/256)
diff --git a/settings.lua b/settings.lua
index 18e9710..232cf02 100644
--- a/settings.lua
+++ b/settings.lua
@@ -72,6 +72,8 @@ mapgen_rivers.settings = {
 	glacier_factor = def_setting('glacier_factor', 'number', 8),
 	elevation_chill = def_setting('elevation_chill', 'number', 0.25),
 
+    grid_x_size = def_setting('grid_x_size', 'number', 1000),
+    grid_z_size = def_setting('grid_z_size', 'number', 1000),
 	evol_params = {
 		K = def_setting('river_erosion_coef', 'number', 0.5),
 		m = def_setting('river_erosion_power', 'number', 0.4),
diff --git a/settingtypes.txt b/settingtypes.txt
index 8650d38..a1df4f1 100644
--- a/settingtypes.txt
+++ b/settingtypes.txt
@@ -9,6 +9,14 @@ mapgen_rivers_center (Center map) bool true
 #    the actual size of the map will be 12000.
 mapgen_rivers_blocksize (Block size) float 15.0 2.0 100.0
 
+#    X size of the grid being generated
+#    Actual size of the map is grid_x_size * blocksize
+mapgen_rivers_grid_x_size (Grid X size) int 1000 50 5000
+
+#    Z size of the grid being generated
+#    Actual size of the map is grid_z_size * blocksize
+mapgen_rivers_grid_z_size (Grid Z size) int 1000 50 5000
+
 #    Minimal catchment area for a river to be drawn, in square nodes
 #    Lower value means bigger river density
 mapgen_rivers_min_catchment (Minimal catchment area) float 3600.0 100.0 1000000.0