diff --git a/app.py b/app.py
index 39a5001..09b1ea3 100644
--- a/app.py
+++ b/app.py
@@ -134,9 +134,9 @@ def load_nifti_cached(path: str, max_voxels: int = 14_000_000) -> Tuple[np.ndarr
     spatial_slices = (slice(None, None, stride), slice(None, None, stride), slice(None, None, stride))
 
     if len(img.shape) == 4:
-        data = np.asarray(img.dataobj[spatial_slices + (slice(None),)], dtype=np.float32)
+        data = np.array(img.dataobj[spatial_slices + (slice(None),)], dtype=np.float32, copy=True)
     else:
-        data = np.asarray(img.dataobj[spatial_slices], dtype=np.float32)
+        data = np.array(img.dataobj[spatial_slices], dtype=np.float32, copy=True)
     data = np.nan_to_num(data, copy=False)
     spacing = tuple(float(v) * stride for v in img.header.get_zooms()[:3])
     return data, spacing, stride  # type: ignore[return-value]