diff --git a/CHANGELOG.md b/CHANGELOG.md
index 93752e1d..063d0e17 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,7 @@
 
 ## Bug Fixes
 
+- [#380](https://github.com/pybop-team/PyBOP/pull/380) - Restore self._boundaries construction for `pybop.PSO`
 - [#372](https://github.com/pybop-team/PyBOP/pull/372) - Converts `np.array` to `np.asarray` for Numpy v2.0 support.
 - [#165](https://github.com/pybop-team/PyBOP/issues/165) - Stores the attempted and best parameter values and the best cost for each iteration in the log attribute of the optimiser and updates the associated plots.
 - [#354](https://github.com/pybop-team/PyBOP/issues/354) - Fixes the calculation of the gradient in the `RootMeanSquaredError` cost.
diff --git a/pybop/optimisers/base_pints_optimiser.py b/pybop/optimisers/base_pints_optimiser.py
index a5140df0..f5698c8e 100644
--- a/pybop/optimisers/base_pints_optimiser.py
+++ b/pybop/optimisers/base_pints_optimiser.py
@@ -134,22 +134,20 @@ def _sanitise_inputs(self):
 
         # Convert bounds to PINTS boundaries
         if self.bounds is not None:
-            if issubclass(
-                self.pints_optimiser,
-                (PintsGradientDescent, PintsAdam, PintsNelderMead),
-            ):
+            ignored_optimisers = (PintsGradientDescent, PintsAdam, PintsNelderMead)
+            if issubclass(self.pints_optimiser, ignored_optimisers):
                 print(f"NOTE: Boundaries ignored by {self.pints_optimiser}")
                 self.bounds = None
-            elif issubclass(self.pints_optimiser, PintsPSO):
-                if not all(
-                    np.isfinite(value)
-                    for sublist in self.bounds.values()
-                    for value in sublist
-                ):
-                    raise ValueError(
-                        "Either all bounds or no bounds must be set for Pints PSO."
-                    )
             else:
+                if issubclass(self.pints_optimiser, PintsPSO):
+                    if not all(
+                        np.isfinite(value)
+                        for sublist in self.bounds.values()
+                        for value in sublist
+                    ):
+                        raise ValueError(
+                            f"Either all bounds or no bounds must be set for {self.pints_optimiser.__name__}."
+                        )
                 self._boundaries = PintsRectangularBoundaries(
                     self.bounds["lower"], self.bounds["upper"]
                 )