diff --git a/api/onnx_web/chain/blend_mask.py b/api/onnx_web/chain/blend_mask.py
index 326ba162..bda9b1ab 100644
--- a/api/onnx_web/chain/blend_mask.py
+++ b/api/onnx_web/chain/blend_mask.py
@@ -1,5 +1,5 @@
 from logging import getLogger
-from typing import Optional
+from typing import Optional, Tuple
 
 from PIL import Image
 
@@ -23,6 +23,7 @@ class BlendMaskStage(BaseStage):
         _params: ImageParams,
         sources: StageResult,
         *,
+        dims: Tuple[int, int, int],
         stage_source: Optional[Image.Image] = None,
         stage_mask: Optional[Image.Image] = None,
         _callback: Optional[ProgressCallback] = None,
@@ -34,13 +35,17 @@ class BlendMaskStage(BaseStage):
         mult_mask = Image.alpha_composite(mult_mask, stage_mask)
         mult_mask = mult_mask.convert("L")
 
+        top, left, tile = dims
+        stage_source_tile = stage_source.crop((top, left, tile, tile))
+
         if is_debug():
             save_image(server, "last-mask.png", stage_mask)
             save_image(server, "last-mult-mask.png", mult_mask)
+            save_image(server, "last-stage-source.png", stage_source_tile)
 
         return StageResult.from_images(
             [
-                Image.composite(stage_source, source, mult_mask)
+                Image.composite(stage_source_tile, source, mult_mask)
                 for source in sources.as_image()
             ]
         )