diff --git a/items.lua b/items.lua
index 1cad510..4a00db0 100644
--- a/items.lua
+++ b/items.lua
@@ -17,9 +17,9 @@ local function show_map_id_formspec(id, player_x, player_z, player_name, marker_
     local map = cartographer.get_map(id);
 
     player_x, player_z = cartographer.to_map_coordinates(map, player_x, player_z)
-    local formspec = cartographer.get_map_formspec_map(data, map, player_x, player_z);
+    local formspec, formspec_width, formspec_height = cartographer.get_map_formspec_map(data, map, player_x, player_z);
     if #_cartographer.marker_lookup > 0 then
-        formspec = formspec .. string.format("style_type[button,image_button,label;noclip=true] container[%f,0.5]", map.w * 0.25) -- TODO: Don't assume map.w * 0.25
+        formspec = formspec .. string.format("style_type[button,image_button,label;noclip=true] container[%f,0.5]", formspec_width - 0.01)
                             .. _cartographer.generate_marker_formspec(cartographer.get_marker(map, player_x, player_z), map.detail, marker_page or 1, cartographer.skin.marker_bg, cartographer.skin.marker_button)
                             .. "container_end[]";
     end
diff --git a/map_formspec.lua b/map_formspec.lua
index 64ee169..29d5c3e 100644
--- a/map_formspec.lua
+++ b/map_formspec.lua
@@ -1,4 +1,5 @@
-local scale = 0.25;
+local TILE_SIZE = 0.25;
+local TILE_OFFSET = 0.24; -- Slightly smaller than TILE_SIZE. We overlap tiles slightly to minimize seams
 
 local variant_odds = { 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4 };
 local function get_variant(random)
@@ -16,8 +17,13 @@ local tile = "image[%f,%f;%f,%f;%s]";
 local marker = "animated_image[%f,%f;%f,%f;;%s;%d;%d]";
 
 -- Generate formspec markup for an unknown biome tile
-local function unknown_biome_tile(x, y, scale, variant)
-    return tile:format(x, y, scale, scale, cartographer.skin.unknown_biome_texture .. "." .. tostring(variant) .. ".png");
+-- x: The x position of the tile
+-- y: The y position of the tile
+-- variant: The tile variant
+--
+-- Returns a formspec string
+local function unknown_biome_tile(x, y, variant)
+    return tile:format(x, y, TILE_SIZE, TILE_SIZE, cartographer.skin.unknown_biome_texture .. "." .. tostring(variant) .. ".png");
 end
 
 -- Generate formspec markup for a given map
@@ -42,12 +48,12 @@ local function generate_map(data, x, y, w, h, player_x, player_y, detail, map_sc
     player_y = math.floor(player_y / map_scale + 0.5);
 
     for i = x,x + w,1 do
-        local fx = (i - x) * (scale - 0.01);
+        local fx = (i - x) * TILE_OFFSET;
         local column = data.generated[i * map_scale];
         for j = y + h,y,-1 do
-            local fy = (y + h - j) * (scale - 0.01);
+            local fy = (y + h - j) * TILE_OFFSET;
             if column == nil or column[j * map_scale] == nil or (is_visible and not is_visible(user, i, j)) then
-                str = str .. unknown_biome_tile(fx, fy, scale, get_variant(random));
+                str = str .. unknown_biome_tile(fx, fy, get_variant(random));
             else
                 local name = minetest.get_biome_name(column[j * map_scale].biome);
                 local height = column[j * map_scale].height;
@@ -62,29 +68,29 @@ local function generate_map(data, x, y, w, h, player_x, player_y, detail, map_sc
                         mod = "^[colorize:white:"..tostring(height * 10)
                         height = height * 0.05;
 
-                        str = str..tile:format(fx, fy - height + (scale - 0.01), scale, height + 0.01, cartographer.skin.cliff_texture .. ".png");
+                        str = str..tile:format(fx, fy - height + TILE_OFFSET, TILE_SIZE, height + 0.01, cartographer.skin.cliff_texture .. ".png");
                     elseif depth > 0 then
                         mod = "^[colorize:#1f1f34:"..tostring(depth * 10)
                     end
 
-                    str = str..tile:format(fx, fy - height, scale, scale, biome .. "." .. tostring(get_variant(random)) .. ".png" .. mod)
+                    str = str..tile:format(fx, fy - height, TILE_SIZE, TILE_SIZE, biome .. "." .. tostring(get_variant(random)) .. ".png" .. mod)
 
                     if get_marker then
                         local marker = cartographer.get_marker_texture(get_marker(user, i, j), detail);
                         if marker then
-                            str = str..tile:format(fx, fy - height, scale, scale, marker .. ".png")
+                            str = str..tile:format(fx, fy - height, TILE_SIZE, TILE_SIZE, marker .. ".png")
                         end
                     end
 
                     if i == player_x and j == player_y then
                         str = str..marker:format(fx, fy - height,
-                                                 scale, scale,
+                                                 TILE_SIZE, TILE_SIZE,
                                                  cartographer.skin.player_icon.texture .. ".png",
                                                  cartographer.skin.player_icon.frame_count,
                                                  cartographer.skin.player_icon.frame_duration);
                     end
                 else
-                    str = str .. unknown_biome_tile(fx, fy, scale, get_variant(random));
+                    str = str .. unknown_biome_tile(fx, fy, get_variant(random));
                 end
             end
         end
@@ -93,10 +99,38 @@ local function generate_map(data, x, y, w, h, player_x, player_y, detail, map_sc
     return str;
 end
 
+-- Get the formspec for a given map segment
+-- data: The map data
+-- x: The X position of the map, in map coordinates
+-- y: The Y position of the map, in map coordinates
+-- w: The width of the map, in map coordinates
+-- h: The height of the map, in map coordinates
+-- detail: The detail level of the map
+--
+-- Returns a formspec string, the width of the formspec, and the height of the
+-- formspec
+-- TODO: Remove data argument
 function cartographer.get_map_formspec(data, x, y, w, h, detail)
-    return map_formspec_prefix:format(w * scale, h * scale)..generate_map(data, x - (w * 0.5), y - (h * 0.5), w, h, x, y, detail, 1);
+    local formspec_width = (w + 1) * TILE_OFFSET + 0.01;
+    local formspec_height = (h + 1) * TILE_OFFSET + 0.01;
+    return map_formspec_prefix:format(formspec_width, formspec_height)..generate_map(data, x - (w * 0.5), y - (h * 0.5), w, h, x, y, detail, 1),
+           formspec_width,
+           formspec_height;
 end
 
+-- Get the formspec for a given map table
+-- data: The map data
+-- map: The map to use
+-- x: The X position of the player marker, in map coordinates
+-- y: The Y position of the player marker, in map coordinates
+--
+-- Returns a formspec string, the width of the formspec, and the height of the
+-- formspec
+-- TODO: Remove data argument
 function cartographer.get_map_formspec_map(data, map, x, y) 
-    return map_formspec_prefix:format(map.w * scale, map.h * scale)..generate_map(data, map.x, map.z, map.w, map.h, x, y, map.detail, map.scale, cartographer.is_filled, cartographer.get_marker, map);
+    local formspec_width = (map.w + 1) * TILE_OFFSET + 0.01;
+    local formspec_height = (map.h + 1) * TILE_OFFSET + 0.01;
+    return map_formspec_prefix:format(formspec_width, formspec_height)..generate_map(data, map.x, map.z, map.w, map.h, x, y, map.detail, map.scale, cartographer.is_filled, cartographer.get_marker, map),
+           formspec_width,
+           formspec_height;
 end