diff --git a/python/metatensor-torch/metatensor/torch/atomistic/ase_calculator.py b/python/metatensor-torch/metatensor/torch/atomistic/ase_calculator.py
index d6da4f7d8..9ed1f9599 100644
--- a/python/metatensor-torch/metatensor/torch/atomistic/ase_calculator.py
+++ b/python/metatensor-torch/metatensor/torch/atomistic/ase_calculator.py
@@ -349,16 +349,16 @@ def calculate(
 
         if do_backward:
             with record_function("ASECalculator::run_backward"):
-                energy.backward(-torch.ones_like(energy))
+                energy.backward()
 
         with record_function("ASECalculator::convert_outputs"):
             if "forces" in properties:
-                forces_values = system.positions.grad.reshape(-1, 3)
+                forces_values = -system.positions.grad.reshape(-1, 3)
                 forces_values = forces_values.to(device="cpu").to(dtype=torch.float64)
                 self.results["forces"] = forces_values.numpy()
 
             if "stress" in properties:
-                stress_values = -strain.grad.reshape(3, 3) / atoms.cell.volume
+                stress_values = strain.grad.reshape(3, 3) / atoms.cell.volume
                 stress_values = stress_values.to(device="cpu").to(dtype=torch.float64)
                 self.results["stress"] = _full_3x3_to_voigt_6_stress(
                     stress_values.numpy()