diff --git a/grassmann_tensor/tensor.py b/grassmann_tensor/tensor.py
index d8bf085..430e465 100644
--- a/grassmann_tensor/tensor.py
+++ b/grassmann_tensor/tensor.py
@@ -78,7 +78,7 @@ def to(self, whatever: torch.device | torch.dtype | str | None = None, *, device
             case str():
                 assert device is None, "Duplicate device specification."
                 device = torch.device(whatever)
-            case None:
+            case _:
                 pass
         match (device, dtype):
             case (None, None):