diff --git a/renderer/Background.ts b/renderer/Background.ts
index 5ed67b8..10e7103 100644
--- a/renderer/Background.ts
+++ b/renderer/Background.ts
@@ -118,6 +118,10 @@ export async function generateBg(
 
   for (let y = 0; y < map.length; y++) {
     for (let x = 0; x < map[y].length; x++) {
+      if (map[y][x] !== "R") {
+        continue;
+      }
+
       const bitMask = getBitMask(map, x, y);
       const tileIdx = BITMASK_TO_TILE_INDEX[bitMask];