diff --git a/pyproject.toml b/pyproject.toml
index 9125259..da754b5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,6 +24,7 @@ dependencies = [
     'appdirs>=1.3',
     'boto3>=1.28,<2',
     'botocore>=1.31,<2',
+    'cloudpickle>=2.1.0',
     'compress-pickle>=1.2.0',
     'humanfriendly>=8.2',
     "numpy>=1.21.0,<2.0.0;python_version<'3.10'",
diff --git a/sdgym/benchmark.py b/sdgym/benchmark.py
index 95aedc9..0660a3f 100644
--- a/sdgym/benchmark.py
+++ b/sdgym/benchmark.py
@@ -7,10 +7,12 @@
 import pickle
 import tracemalloc
 import warnings
+from contextlib import contextmanager
 from datetime import datetime
 from pathlib import Path
 
 import boto3
+import cloudpickle
 import compress_pickle
 import numpy as np
 import pandas as pd
@@ -318,6 +320,26 @@ def _score(
     return output
 
 
+@contextmanager
+def multiprocessing_context():
+    """Override multiprocessing ForkingPickler to use cloudpickle."""
+    original_dump = multiprocessing.reduction.ForkingPickler.dumps
+    original_load = multiprocessing.reduction.ForkingPickler.loads
+    original_method = multiprocessing.get_start_method()
+
+    multiprocessing.set_start_method('spawn', force=True)
+    multiprocessing.reduction.ForkingPickler.dumps = cloudpickle.dumps
+    multiprocessing.reduction.ForkingPickler.loads = cloudpickle.loads
+
+    try:
+        yield
+    finally:
+        # Restore original methods
+        multiprocessing.set_start_method(original_method, force=True)
+        multiprocessing.reduction.ForkingPickler.dumps = original_dump
+        multiprocessing.reduction.ForkingPickler.loads = original_load
+
+
 def _score_with_timeout(
     timeout,
     synthesizer,
@@ -329,32 +351,33 @@ def _score_with_timeout(
     modality=None,
     dataset_name=None,
 ):
-    with multiprocessing.Manager() as manager:
-        output = manager.dict()
-        process = multiprocessing.Process(
-            target=_score,
-            args=(
-                synthesizer,
-                data,
-                metadata,
-                metrics,
-                output,
-                compute_quality_score,
-                compute_diagnostic_score,
-                modality,
-                dataset_name,
-            ),
-        )
+    with multiprocessing_context():
+        with multiprocessing.Manager() as manager:
+            output = manager.dict()
+            process = multiprocessing.Process(
+                target=_score,
+                args=(
+                    synthesizer,
+                    data,
+                    metadata,
+                    metrics,
+                    output,
+                    compute_quality_score,
+                    compute_diagnostic_score,
+                    modality,
+                    dataset_name,
+                ),
+            )
 
-        process.start()
-        process.join(timeout)
-        process.terminate()
+            process.start()
+            process.join(timeout)
+            process.terminate()
 
-        output = dict(output)
-        if output.get('timeout'):
-            LOGGER.error('Timeout running %s on dataset %s;', synthesizer['name'], dataset_name)
+            output = dict(output)
+            if output.get('timeout'):
+                LOGGER.error('Timeout running %s on dataset %s;', synthesizer['name'], dataset_name)
 
-        return output
+            return output
 
 
 def _format_output(
diff --git a/sdgym/synthesizers/generate.py b/sdgym/synthesizers/generate.py
index 63baced..718fe7b 100644
--- a/sdgym/synthesizers/generate.py
+++ b/sdgym/synthesizers/generate.py
@@ -124,7 +124,7 @@ def get_trained_synthesizer(self, data, metadata):
                 obj:
                     The trained synthesizer.
             """
-            return get_trained_synthesizer_fn(data, metadata)
+            return self.synthesizer_fn['get_trained_synthesizer_fn'](data, metadata)
 
         def sample_from_synthesizer(self, synthesizer, num_samples):
             """Sample the desired number of samples from the given synthesizer.
@@ -139,11 +139,22 @@ def sample_from_synthesizer(self, synthesizer, num_samples):
                 pandas.DataFrame:
                     The synthetic data.
             """
-            return sample_from_synthesizer_fn(synthesizer, num_samples)
-
-    NewSynthesizer.__name__ = f'Custom:{display_name}'
-
-    return NewSynthesizer
+            return self.synthesizer_fn['sample_from_synthesizer_fn'](synthesizer, num_samples)
+
+    CustomSynthesizer = type(
+        f'Custom:{display_name}',
+        (NewSynthesizer,),
+        {
+            'synthesizer_fn': {
+                'get_trained_synthesizer_fn': get_trained_synthesizer_fn,
+                'sample_from_synthesizer_fn': sample_from_synthesizer_fn,
+            },
+        },
+    )
+    CustomSynthesizer.__name__ = f'Custom:{display_name}'
+    CustomSynthesizer.__module__ = 'sdgym.synthesizers.generate'
+    globals()[f'Custom:{display_name}'] = CustomSynthesizer
+    return CustomSynthesizer
 
 
 def create_multi_table_synthesizer(