diff --git a/frontend/src/png/inventory.ts b/frontend/src/png/inventory.ts
index 9c6ccef..c68ffab 100644
--- a/frontend/src/png/inventory.ts
+++ b/frontend/src/png/inventory.ts
@@ -50,6 +50,7 @@ export function composeInventoryFrame(
       const sx = Math.floor(x0 + (x + 0.5 - ox) / scale);
       const sy = Math.floor(y0 + (y + 0.5 - oy) / scale);
       if (sx < 0 || sy < 0 || sx >= source.widthPx || sy >= source.heightPx) continue;
+      if (mask.bitset[sy * source.widthPx + sx] !== 1) continue;
       const si = (sy * source.widthPx + sx) * 4;
       const di = (y * outW + x) * 4;
       rgba[di] = src.rgba[si];