diff --git a/torchvision/prototype/datasets/_builtin/dtd.py b/torchvision/prototype/datasets/_builtin/dtd.py
index 36990e8a21d..fc3ec61efc7 100644
--- a/torchvision/prototype/datasets/_builtin/dtd.py
+++ b/torchvision/prototype/datasets/_builtin/dtd.py
@@ -72,7 +72,8 @@ def _classify_archive(self, data: Tuple[str, Any]) -> Optional[int]:
 
     def _image_key_fn(self, data: Tuple[str, Any]) -> str:
         path = pathlib.Path(data[0])
-        return str(path.relative_to(path.parents[1]))
+        # The split files contain hardcoded posix paths for the images, e.g. banded/banded_0001.jpg
+        return str(path.relative_to(path.parents[1]).as_posix())
 
     def _collate_and_decode_sample(
         self,