diff --git a/init.lua b/init.lua
index 0005907..3611148 100644
--- a/init.lua
+++ b/init.lua
@@ -7,25 +7,21 @@ local modpath = minetest.get_modpath("cartographer");
 cartographer = {
     scan_queue = {},
 };
-_cartographer = {
-    maps = minetest.deserialize(mod_storage:get_string("maps")) or {},
-    next_map_id = mod_storage:get_int("next_map_id"),
-
-    materials_by_name = {},
-    materials_by_group = {},
-};
-
-if _cartographer.next_map_id == 0 then
-    _cartographer.next_map_id = 1;
-end
 
 local map_data = {
     generated = minetest.deserialize(mod_storage:get_string("map")) or {},
+
+    maps = minetest.deserialize(mod_storage:get_string("maps")) or {},
+    next_map_id = mod_storage:get_int("next_map_id"),
 }
 
+if map_data.next_map_id == 0 then
+    map_data.next_map_id = 1;
+end
+
 local function save()
-    mod_storage:set_string("maps", minetest.serialize(_cartographer.maps));
-    mod_storage:set_int("next_map_id", _cartographer.next_map_id);
+    mod_storage:set_string("maps", minetest.serialize(map_data.maps));
+    mod_storage:set_int("next_map_id", map_data.next_map_id);
     mod_storage:set_string("map", minetest.serialize(map_data.generated));
 end
 minetest.register_on_shutdown(save);
@@ -58,8 +54,8 @@ local gui = loadfile(modpath .. "/formspec.lua") ();
 cartographer.skin = skin;
 
 loadfile(modpath .. "/scanner.lua") (map_data, chunk);
-loadfile(modpath .. "/map_api.lua") (chunk, biome_lookup, marker_lookup);
+loadfile(modpath .. "/map_api.lua") (map_data, chunk, biome_lookup, marker_lookup);
 local map_formspec = loadfile(modpath .. "/map_formspec.lua") (map_data, gui, skin);
 loadfile(modpath .. "/items.lua") (chunk, marker_lookup, gui, skin, map_formspec);
 loadfile(modpath .. "/commands.lua") (map_formspec);
-loadfile(modpath .. "/table.lua") (_cartographer.materials_by_name, _cartographer.materials_by_group, gui, skin);
+loadfile(modpath .. "/table.lua") (gui, skin);
diff --git a/map_api.lua b/map_api.lua
index f335408..f2620a9 100644
--- a/map_api.lua
+++ b/map_api.lua
@@ -1,7 +1,7 @@
-local chunk, biome_lookup, marker_lookup = ...;
+local map_data, chunk, biome_lookup, marker_lookup = ...;
 
 function cartographer.create_map(x, z, w, h, filled, detail, scale)
-    local id = _cartographer.next_map_id;
+    local id = map_data.next_map_id;
 
     local map = {
         id = id,
@@ -15,18 +15,18 @@ function cartographer.create_map(x, z, w, h, filled, detail, scale)
         markers = {},
     };
 
-    _cartographer.maps[id] = map;
+    map_data.maps[id] = map;
     if filled then
         cartographer.fill(map, x, z, w, h);
     end
 
-    _cartographer.next_map_id = _cartographer.next_map_id + 1;
+    map_data.next_map_id = map_data.next_map_id + 1;
 
     return id;
 end
 
 function cartographer.get_map(id)
-    return _cartographer.maps[id];
+    return map_data.maps[id];
 end
 
 function cartographer.resize_map(id, w, h)
diff --git a/table.lua b/table.lua
index 7a14995..b18ed30 100644
--- a/table.lua
+++ b/table.lua
@@ -1,4 +1,4 @@
-local materials_by_name, materials_by_group, gui, gui_skin = ...;
+local gui, gui_skin = ...;
 
 local MAP_SIZE = 40;
 local SCALE_SMALL = 1;
@@ -6,6 +6,9 @@ local SCALE_MEDIUM = 2;
 local SCALE_LARGE = 4;
 local SCALE_HUGE = 8;
 
+local materials_by_name = {};
+local materials_by_group = {};
+
 -- Get the material cost for the given map scale and detail level
 -- scale: The map scale
 -- detail: The detail level