diff --git a/setup.py b/setup.py
index 7e7470d3..e330482a 100644
--- a/setup.py
+++ b/setup.py
@@ -8,6 +8,7 @@
     description='Training and inference tools for generative audio models from Stability AI',
     packages=find_packages(),  
     install_requires=[
+        'dill',
         'aeiou==0.0.20',
         'alias-free-torch==0.0.6',
         'auraloss==0.4.0',
@@ -41,4 +42,4 @@
         'webdataset==0.2.48',
         'x-transformers<1.27.0'
     ],
-)
\ No newline at end of file
+)
diff --git a/stable_audio_tools/data/dataset.py b/stable_audio_tools/data/dataset.py
index 4bc535a1..bc7c0c88 100644
--- a/stable_audio_tools/data/dataset.py
+++ b/stable_audio_tools/data/dataset.py
@@ -1,4 +1,5 @@
 import importlib
+import dill
 import numpy as np
 import io
 import os
@@ -155,7 +156,7 @@ def __init__(
             self.root_paths.append(config.path)
             self.filenames.extend(get_audio_filenames(config.path, keywords))
             if config.custom_metadata_fn is not None:
-                self.custom_metadata_fns[config.path] = config.custom_metadata_fn
+                self.custom_metadata_fns[config.path] = dill.dumps(config.custom_metadata_fn)
 
         print(f'Found {len(self.filenames)} files')
 
@@ -216,8 +217,8 @@ def __getitem__(self, idx):
 
             for custom_md_path in self.custom_metadata_fns.keys():
                 if custom_md_path in audio_filename:
-                    custom_metadata_fn = self.custom_metadata_fns[custom_md_path]
-                    custom_metadata = custom_metadata_fn(info, audio)
+                    custom_metadata_fn_deserialized = dill.loads(self.custom_metadata_fns[custom_md_path])
+                    custom_metadata = custom_metadata_fn_deserialized(info, audio)
                     info.update(custom_metadata)
 
                 if "__reject__" in info and info["__reject__"]:
@@ -651,4 +652,4 @@ def create_dataloader_from_config(dataset_config, batch_size, sample_size, sampl
             persistent_workers=True,
             force_channels=force_channels,
             epoch_steps=dataset_config.get("epoch_steps", 2000)
-        ).data_loader
\ No newline at end of file
+        ).data_loader