diff --git a/tianshou/algorithm/modelfree/trpo.py b/tianshou/algorithm/modelfree/trpo.py
index 450fdde54..6ba0a2259 100644
--- a/tianshou/algorithm/modelfree/trpo.py
+++ b/tianshou/algorithm/modelfree/trpo.py
@@ -183,7 +183,7 @@ def _update_with_batch(  # type: ignore[override]
                         if i < self.max_backtracks - 1:
                             step_size = step_size * self.backtrack_coeff
                         else:
-                            self._set_from_flat_params(self.policy.actor, new_flat_params)
+                            self._set_from_flat_params(self.policy.actor, flat_params)
                             step_size = torch.tensor([0.0])
                             warnings.warn(
                                 "Line search failed! It seems hyperparamters"