diff --git a/items.lua b/items.lua
index c01f1f0..519fa40 100644
--- a/items.lua
+++ b/items.lua
@@ -116,14 +116,18 @@ end
 -- height_mode: Whether or not to display the map in height mode
 -- (Optional) marker_page: The current page that the marker editor is on
 local function show_map_id_formspec(id, player_x, player_z, player_name, height_mode, marker_page)
-    cartographer.fill_local(id, player_x, player_z);
+    local map = cartographer.get_map(id);
+    if not map then
+        return
+    end
+
+    map:fill_local(id, player_x, player_z);
 
     player_maps[player_name] = {
         id = id,
         page = marker_page or 1,
         height_mode = height_mode,
     };
-    local map = cartographer.get_map(id);
 
     player_x, player_z = map:to_coordinates(player_x, player_z)
     local formspec, formspec_width, _ = map_formspec.from_map(map, player_x, player_z, height_mode);
diff --git a/map_api.lua b/map_api.lua
index 6686f82..1ebc43e 100644
--- a/map_api.lua
+++ b/map_api.lua
@@ -79,18 +79,12 @@ end
 -- id: A map ID
 -- x: The x position, in world coordinates
 -- z: The z position, in world coordinates
-function cartographer.fill_local(id, x, z)
-    local map = cartographer.get_map(id);
-
-    if not map then
-        return;
-    end
-
-    x, z = map:to_coordinates(x, z);
+function Map.fill_local(self, x, z)
+    x, z = self:to_coordinates(x, z);
 
     -- TODO: Adjust size to match map scale
-    if x >= map.x - 2 and x <= map.x + map.w + 1 and z >= map.z - 2 and z <= map.z + map.h + 1 then
-        map:fill_area(x - 2, z - 2, 5, 5);
+    if x >= self.x - 2 and x <= self.x + self.w + 1 and z >= self.z - 2 and z <= self.z + self.h + 1 then
+        self:fill_area(x - 2, z - 2, 5, 5);
     end
 end
 
@@ -118,9 +112,10 @@ local function fill_loop()
         if pos.y > -10 then
             for i = 1,inventory:get_size("main") do
                 local stack = inventory:get_stack("main", i);
+                local map = cartographer.get_map(stack:get_meta():get_int("cartographer:map_id"));
 
-                if stack:get_name() == "cartographer:map" then
-                    cartographer.fill_local(stack:get_meta():get_int("cartographer:map_id"), pos.x, pos.z);
+                if map then
+                    map:fill_local(pos.x, pos.z);
                 end
             end
             for i = -2,2 do