diff --git a/examples/01-charges-example.py b/examples/01-charges-example.py
index 53d6b964..6465a507 100644
--- a/examples/01-charges-example.py
+++ b/examples/01-charges-example.py
@@ -39,10 +39,11 @@
 import torchpme
 from torchpme.tuning import tune_pme
 
+dtype = torch.float64
+
 # %%
 #
 # Create the properties CsCl unit cell
-dtype = torch.float64
 symbols = ("Cs", "Cl")
 types = torch.tensor([55, 17])
 charges = torch.tensor([[1.0], [-1.0]], dtype=dtype)
diff --git a/src/torchpme/_utils.py b/src/torchpme/_utils.py
index f282a626..8d42e45c 100644
--- a/src/torchpme/_utils.py
+++ b/src/torchpme/_utils.py
@@ -15,7 +15,7 @@ def _validate_parameters(
 ) -> None:
     if positions.dtype != dtype:
         raise TypeError(
-            f"type of `positions` ({positions.dtype}) must be same as class "
+            f"type of `positions` ({positions.dtype}) must be same as the class "
             f"type ({dtype})"
         )
 
@@ -24,10 +24,13 @@ def _validate_parameters(
 
     if positions.device.type != device:
         raise ValueError(
-            f"device of `positions` ({positions.device}) must be same as class "
+            f"device of `positions` ({positions.device}) must be same as the class "
             f"device ({device})"
         )
 
+    # We use `positions.device` because it includes the device type AND index, which the
+    # `device` parameter may lack
+
     # check shape, dtype and device of positions
     num_atoms = len(positions)
     if list(positions.shape) != [len(positions), 3]:
@@ -45,12 +48,12 @@ def _validate_parameters(
 
     if cell.dtype != positions.dtype:
         raise TypeError(
-            f"type of `cell` ({cell.dtype}) must be same as `positions` ({dtype})"
+            f"type of `cell` ({cell.dtype}) must be same as the class ({dtype})"
         )
 
     if cell.device != positions.device:
         raise ValueError(
-            f"device of `cell` ({cell.device}) must be same as `positions` ({device})"
+            f"device of `cell` ({cell.device}) must be same as the class ({device})"
         )
 
     if smearing is not None and torch.equal(
@@ -79,12 +82,12 @@ def _validate_parameters(
 
     if charges.dtype != positions.dtype:
         raise TypeError(
-            f"type of `charges` ({charges.dtype}) must be same as `positions` ({dtype})"
+            f"type of `charges` ({charges.dtype}) must be same as the class ({dtype})"
         )
 
     if charges.device != positions.device:
         raise ValueError(
-            f"device of `charges` ({charges.device}) must be same as `positions` "
+            f"device of `charges` ({charges.device}) must be same as the class "
             f"({device})"
         )
 
@@ -99,7 +102,7 @@ def _validate_parameters(
     if neighbor_indices.device != positions.device:
         raise ValueError(
             f"device of `neighbor_indices` ({neighbor_indices.device}) must be "
-            f"same as `positions` ({device})"
+            f"same as the class ({device})"
         )
 
     if neighbor_distances.shape != neighbor_indices[:, 0].shape:
@@ -112,11 +115,11 @@ def _validate_parameters(
     if neighbor_distances.device != positions.device:
         raise ValueError(
             f"device of `neighbor_distances` ({neighbor_distances.device}) must be "
-            f"same as `positions` ({device})"
+            f"same as the class ({device})"
         )
 
     if neighbor_distances.dtype != positions.dtype:
         raise TypeError(
             f"type of `neighbor_distances` ({neighbor_distances.dtype}) must be same "
-            f"as `positions` ({dtype})"
+            f"as the class ({dtype})"
         )
diff --git a/tests/calculators/test_calculator.py b/tests/calculators/test_calculator.py
index 567b0f15..dff72455 100644
--- a/tests/calculators/test_calculator.py
+++ b/tests/calculators/test_calculator.py
@@ -45,7 +45,7 @@ def test_compute_output_shapes():
 
 def test_wrong_device_positions():
     calculator = CalculatorTest()
-    match = r"device of `positions` \(meta\) must be same as class device \(cpu\)"
+    match = r"device of `positions` \(meta\) must be same as the class device \(cpu\)"
     with pytest.raises(ValueError, match=match):
         calculator.forward(
             positions=POSITIONS_1.to(device="meta"),
@@ -59,7 +59,7 @@ def test_wrong_device_positions():
 def test_wrong_dtype_positions():
     calculator = CalculatorTest()
     match = (
-        r"type of `positions` \(torch.float64\) must be same as class type "
+        r"type of `positions` \(torch.float64\) must be same as the class type "
         r"\(torch.float32\)"
     )
     with pytest.raises(TypeError, match=match):
@@ -108,8 +108,7 @@ def test_invalid_shape_cell():
 def test_invalid_dtype_cell():
     calculator = CalculatorTest()
     match = (
-        r"type of `cell` \(torch.float64\) must be same as `positions` "
-        r"\(torch.float32\)"
+        r"type of `cell` \(torch.float64\) must be same as the class \(torch.float32\)"
     )
     with pytest.raises(TypeError, match=match):
         calculator.forward(
@@ -123,7 +122,7 @@ def test_invalid_dtype_cell():
 
 def test_invalid_device_cell():
     calculator = CalculatorTest()
-    match = r"device of `cell` \(meta\) must be same as `positions` \(cpu\)"
+    match = r"device of `cell` \(meta\) must be same as the class \(cpu\)"
     with pytest.raises(ValueError, match=match):
         calculator.forward(
             positions=POSITIONS_1,
@@ -189,7 +188,7 @@ def test_invalid_shape_charges():
 def test_invalid_dtype_charges():
     calculator = CalculatorTest()
     match = (
-        r"type of `charges` \(torch.float64\) must be same as `positions` "
+        r"type of `charges` \(torch.float64\) must be same as the class "
         r"\(torch.float32\)"
     )
     with pytest.raises(TypeError, match=match):
@@ -204,7 +203,7 @@ def test_invalid_dtype_charges():
 
 def test_invalid_device_charges():
     calculator = CalculatorTest()
-    match = r"device of `charges` \(meta\) must be same as `positions` \(cpu\)"
+    match = r"device of `charges` \(meta\) must be same as the class \(cpu\)"
     with pytest.raises(ValueError, match=match):
         calculator.forward(
             positions=POSITIONS_1,
@@ -249,7 +248,7 @@ def test_invalid_shape_neighbor_indices_neighbor_distances():
 
 def test_invalid_device_neighbor_indices():
     calculator = CalculatorTest()
-    match = r"device of `neighbor_indices` \(meta\) must be same as `positions` \(cpu\)"
+    match = r"device of `neighbor_indices` \(meta\) must be same as the class \(cpu\)"
     with pytest.raises(ValueError, match=match):
         calculator.forward(
             positions=POSITIONS_1,
@@ -262,9 +261,7 @@ def test_invalid_device_neighbor_indices():
 
 def test_invalid_device_neighbor_distances():
     calculator = CalculatorTest()
-    match = (
-        r"device of `neighbor_distances` \(meta\) must be same as `positions` \(cpu\)"
-    )
+    match = r"device of `neighbor_distances` \(meta\) must be same as the class \(cpu\)"
     with pytest.raises(ValueError, match=match):
         calculator.forward(
             positions=POSITIONS_1,
@@ -279,7 +276,7 @@ def test_invalid_dtype_neighbor_distances():
     calculator = CalculatorTest()
     match = (
         r"type of `neighbor_distances` \(torch.float64\) must be same "
-        r"as `positions` \(torch.float32\)"
+        r"as the class \(torch.float32\)"
     )
     with pytest.raises(TypeError, match=match):
         calculator.forward(