diff --git a/changelog.d/vtk-holds-device-memory.md b/changelog.d/vtk-holds-device-memory.md
new file mode 100644
index 00000000..c6841c6b
--- /dev/null
+++ b/changelog.d/vtk-holds-device-memory.md
@@ -0,0 +1,8 @@
+### Fixed
+
+- A VTK with DLPack but without the device's memory (the nightly wheels, whose
+  Viskores runs on the CPU alone yet lists CUDA among
+  `dlpack_support.supported_device_types()`) no longer fails every VTK
+  algorithm on a GPU as it hands its output back: the interop tries a
+  four-value array once per type of device (`_vtk_holds`) and copies to the
+  host where VTK cannot hold the memory.
diff --git a/packages/tack-core/tests/test_arrays_protocol.py b/packages/tack-core/tests/test_arrays_protocol.py
index 417dcdd2..8e0de3ba 100644
--- a/packages/tack-core/tests/test_arrays_protocol.py
+++ b/packages/tack-core/tests/test_arrays_protocol.py
@@ -239,7 +239,10 @@ def test_implicit_arrays_index_from_the_host_as_arrays_do():
              ta.CountingArray(5, start=3, step=2),
              ta.UniformCoordinates((3, 2, 2), origin=(1, 0, 0), spacing=(0.5, 1, 1)),
              ta.CartesianProduct([0.0, 1.0, 3.0], [0.0, 2.0]),
-             ta.Permutation(stored, tack.array(np.array([5, 0, 3], np.int32)))]
+             ta.Permutation(tack.array(np.array([5, 0, 3], np.int32)), stored)]
+    # Ids first: given the other way round, the floats were ids into the three
+    # ids, read out of bounds alike on the host and in the kernel (TACK_DEBUG).
+    np.testing.assert_array_equal(ta.to_host(cases[-1]), [7.5, 0.0, 4.5])
     for values in cases:
         host = np.asarray(ta.to_host(values))
         assert len(values) == host.shape[0]
diff --git a/packages/tack-vis/examples/51_vtk_openfoam.py b/packages/tack-vis/examples/51_vtk_openfoam.py
index 01380083..df95880c 100644
--- a/packages/tack-vis/examples/51_vtk_openfoam.py
+++ b/packages/tack-vis/examples/51_vtk_openfoam.py
@@ -29,6 +29,7 @@
 """
 
 import argparse
+import os
 
 import numpy as np
 
@@ -79,7 +80,9 @@ def area(surface):
 # THE CASE, WITH ITS PATCHES
 # ================================================================
 
-reader = vtkOpenFOAMReader(file_name=_vtk_data.path("OpenFOAM/squareBend/squareBend.foam"))
+# The case's directory, so that every file of the case is fetched.
+reader = vtkOpenFOAMReader(
+    file_name=os.path.join(_vtk_data.path("OpenFOAM/squareBend"), "squareBend.foam"))
 reader.UpdateInformation()
 for i in range(reader.GetNumberOfPatchArrays()):
     reader.SetPatchArrayStatus(reader.GetPatchArrayName(i), 1)
diff --git a/packages/tack-vis/examples/52_vtk_pathlines.py b/packages/tack-vis/examples/52_vtk_pathlines.py
index 20258996..af6e0fbd 100644
--- a/packages/tack-vis/examples/52_vtk_pathlines.py
+++ b/packages/tack-vis/examples/52_vtk_pathlines.py
@@ -30,6 +30,7 @@
 """
 
 import argparse
+import os
 
 import numpy as np
 
@@ -77,7 +78,9 @@ def ends(lines):
 # THE CASE
 # ================================================================
 
-reader = vtkOpenFOAMReader(file_name=_vtk_data.path("OpenFOAM/cavity/cavity.foam"))
+# The case's directory, so that every file of the case is fetched.
+reader = vtkOpenFOAMReader(
+    file_name=os.path.join(_vtk_data.path("OpenFOAM/cavity"), "cavity.foam"))
 reader.UpdateInformation()
 steps = list(reader.GetOutputInformation(0).Get(
     vtkStreamingDemandDrivenPipeline.TIME_STEPS()))
diff --git a/packages/tack-vis/src/tack/interop/vtk/__init__.py b/packages/tack-vis/src/tack/interop/vtk/__init__.py
index 19a0c847..83804a52 100644
--- a/packages/tack-vis/src/tack/interop/vtk/__init__.py
+++ b/packages/tack-vis/src/tack/interop/vtk/__init__.py
@@ -2059,7 +2059,27 @@ def _stored_on_device(values):
         _dlpack_support()
     except RuntimeError:
         return False
-    return True
+    return _vtk_holds(values.device)
+
+
+#: Whether this VTK holds each type of device's memory in its arrays, by the type.
+_holds = {}
+
+
+def _vtk_holds(device):
+    """Whether this VTK makes arrays of ``device``'s memory: a four-value array is
+    tried once for each type of device. A VTK with DLPack whose Viskores has no such
+    device (the nightly wheels', on the CPU alone) still lists the type in
+    ``dlpack_support.supported_device_types()``, and refuses it only when asked."""
+    if device.type not in _holds:
+        try:
+            # Not array_to_vtk: a Level Zero context VTK does not share is its
+            # error to give, where the array is made.
+            probe = _dlpack_support().dlpack_to_vtk(tack.zeros((4, 1), device=device))
+            _holds[device.type] = _device_type(probe) == device.type
+        except (ImportError, RuntimeError):
+            _holds[device.type] = False
+    return _holds[device.type]
 
 
 def _vtk_cells(offsets, connectivity, share=False):
diff --git a/packages/tack-vis/tests/test_vtk_interop.py b/packages/tack-vis/tests/test_vtk_interop.py
index 4e376890..9bd2b2a8 100644
--- a/packages/tack-vis/tests/test_vtk_interop.py
+++ b/packages/tack-vis/tests/test_vtk_interop.py
@@ -368,7 +368,8 @@ def _init_device(arch):
 
 
 def _device_arches():
-    """Backends on this machine whose memory VTK can describe."""
+    """Backends on this machine whose memory VTK can describe, and holds: a VTK whose
+    Viskores runs on the CPU alone (the nightly wheels') has DLPack but no device."""
     from tack.runtime.dispatch import get_backend
 
     found = []
@@ -377,7 +378,8 @@ def _device_arches():
             _init_device(arch)
         except (ImportError, RuntimeError, OSError, AttributeError):
             continue  # not built, no device, no driver, or no shared context
-        if get_backend().device_memory_spaces:
+        if get_backend().device_memory_spaces and interop._vtk_holds(
+                tack.get_default_device()):
             found.append(pytest.param(arch, space, id=arch))
     tack.set_default_device("cpu")
     return found