diff --git a/src/somd2/runner/_repex.py b/src/somd2/runner/_repex.py
index c568111..62fbded 100644
--- a/src/somd2/runner/_repex.py
+++ b/src/somd2/runner/_repex.py
@@ -277,8 +277,8 @@ def run(self):
         from math import ceil
         from time import time
 
-        from concurrent.futures import ThreadPoolExecutor as _ThreadPoolExecutor
-        from itertools import repeat as _repeat
+        from concurrent.futures import ThreadPoolExecutor
+        from itertools import repeat
 
         # Record the start time.
         start = time()
@@ -320,8 +320,8 @@ def run(self):
             num_blocks = 1
             rem = 0
 
-        # Work out the required number of executors.
-        executors = ceil(
+        # Work out the required number of batches.
+        num_batches = ceil(
             self._config.num_lambda
             / (self._num_gpus * self._config.oversubscription_factor)
         )
@@ -331,19 +331,29 @@ def run(self):
 
         # Minimise at each lambda value.
         if self._config.minimise:
-            with _ThreadPoolExecutor(max_workers=self._num_gpus) as executor:
-                try:
-                    for result, index, exception in executor.map(
-                        self._minimise, replica_list
-                    ):
-                        if not result:
-                            _logger.error(
-                                f"Minimisation failed for {_lam_sym} = {self._lambda_values[index]:.5f}: {exception}"
-                            )
-                            raise exception
-                except KeyboardInterrupt:
-                    _logger.error("Minimisation cancelled. Exiting.")
-                    exit(1)
+            # Run minimisation for each replica, making sure only each GPU is only
+            # oversubscribed by a factor of self._config.oversubscription_factor.
+            for i in range(num_batches):
+                with ThreadPoolExecutor() as executor:
+                    try:
+                        for result, index, exception in executor.map(
+                            self._minimise,
+                            replica_list[
+                                i
+                                * self._num_gpus
+                                * self._config.oversubscription_factor : (i + 1)
+                                * self._num_gpus
+                                * self._config.oversubscription_factor
+                            ],
+                        ):
+                            if not result:
+                                _logger.error(
+                                    f"Minimisation failed for {_lam_sym} = {self._lambda_values[index]:.5f}: {exception}"
+                                )
+                                raise exception
+                    except KeyboardInterrupt:
+                        _logger.error("Minimisation cancelled. Exiting.")
+                        exit(1)
 
         # Current block number.
         block = 0
@@ -369,7 +379,7 @@ def run(self):
 
             # Run a dynamics block for each replica, making sure only each GPU is only
             # oversubscribed by a factor of self._config.oversubscription_factor.
-            for j in range(executors):
+            for j in range(num_batches):
                 replicas = replica_list[
                     j
                     * self._num_gpus
@@ -377,18 +387,16 @@ def run(self):
                     * self._num_gpus
                     * self._config.oversubscription_factor
                 ]
-                with _ThreadPoolExecutor(
-                    max_workers=self._num_gpus * self._config.oversubscription_factor
-                ) as executor:
+                with ThreadPoolExecutor() as executor:
                     try:
                         for result, index, energies in executor.map(
                             self._run_block,
                             replicas,
-                            _repeat(self._lambda_values),
-                            _repeat(is_checkpoint),
-                            _repeat(i == cycles - 1),
-                            _repeat(block),
-                            _repeat(num_blocks + int(rem > 0)),
+                            repeat(self._lambda_values),
+                            repeat(is_checkpoint),
+                            repeat(i == cycles - 1),
+                            repeat(block),
+                            repeat(num_blocks + int(rem > 0)),
                         ):
                             if not result:
                                 _logger.error(