diff --git a/casanovo/casanovo.py b/casanovo/casanovo.py
index 72b02057..0be7a784 100644
--- a/casanovo/casanovo.py
+++ b/casanovo/casanovo.py
@@ -15,10 +15,8 @@
 import click
 import github
 import requests
-import torch
 import tqdm
-import yaml
-from pytorch_lightning.lite import LightningLite
+from lightning import Fabric
 
 from . import __version__
 from . import utils
@@ -127,7 +125,7 @@ def main(
     # Read parameters from the config file.
     config = Config(config)
 
-    LightningLite.seed_everything(seed=config["random_seed"], workers=True)
+    Fabric.seed_everything(seed=config["random_seed"], workers=True)
 
     # Download model weights if these were not specified (except when training).
     if model is None and mode != "train":
diff --git a/casanovo/config.py b/casanovo/config.py
index 4dc93c26..352d6743 100644
--- a/casanovo/config.py
+++ b/casanovo/config.py
@@ -50,6 +50,7 @@ class Config:
         dropout=float,
         dim_intensity=int,
         max_length=int,
+        residues=dict,  # note, this key is special-cased and type is ignored
         n_log=int,
         tb_summarywriter=str,
         warmup_iters=int,
diff --git a/casanovo/denovo/model.py b/casanovo/denovo/model.py
index 8b3ae3e0..32a50b31 100644
--- a/casanovo/denovo/model.py
+++ b/casanovo/denovo/model.py
@@ -724,8 +724,8 @@ def training_step(
         pred = pred[:, :-1, :].reshape(-1, self.decoder.vocab_size + 1)
         loss = self.celoss(pred, truth.flatten())
         self.log(
-            "CELoss",
-            {mode: loss.detach()},
+            f"CELoss/{mode}",
+            loss.detach(),
             on_step=False,
             on_epoch=True,
             sync_dist=True,
@@ -765,13 +765,11 @@ def validation_step(
         )
         log_args = dict(on_step=False, on_epoch=True, sync_dist=True)
         self.log(
-            "Peptide precision at coverage=1",
-            {"valid": pep_precision},
+            "Peptide precision at coverage=1/valid",
+            pep_precision,
             **log_args,
         )
-        self.log(
-            "AA precision at coverage=1", {"valid": aa_precision}, **log_args
-        )
+        self.log("AA precision at coverage=1/valid", aa_precision, **log_args)
 
         return loss
 
@@ -824,7 +822,7 @@ def on_train_epoch_end(self) -> None:
         """
         Log the training loss at the end of each epoch.
         """
-        train_loss = self.trainer.callback_metrics["CELoss"]["train"].detach()
+        train_loss = self.trainer.callback_metrics["CELoss/train"].detach()
         metrics = {
             "step": self.trainer.global_step,
             "train": train_loss,
@@ -839,20 +837,18 @@ def on_validation_epoch_end(self) -> None:
         callback_metrics = self.trainer.callback_metrics
         metrics = {
             "step": self.trainer.global_step,
-            "valid": callback_metrics["CELoss"]["valid"].detach(),
+            "valid": callback_metrics["CELoss/valid"].detach(),
             "valid_aa_precision": callback_metrics[
-                "AA precision at coverage=1"
-            ]["valid"].detach(),
+                "AA precision at coverage=1/valid"
+            ].detach(),
             "valid_pep_precision": callback_metrics[
-                "Peptide precision at coverage=1"
-            ]["valid"].detach(),
+                "Peptide precision at coverage=1/valid"
+            ].detach(),
         }
         self._history.append(metrics)
         self._log_history()
 
-    def on_predict_epoch_end(
-        self, results: List[List[Tuple[np.ndarray, List[str], torch.Tensor]]]
-    ) -> None:
+    def on_predict_epoch_end(self) -> None:
         """
         Write the predicted peptide sequences and amino acid scores to the
         output file.
@@ -868,7 +864,7 @@ def on_predict_epoch_end(
             peptide_score,
             aa_scores,
         ) in itertools.chain.from_iterable(
-            itertools.chain.from_iterable(results)
+            self.trainer.predict_loop.predictions
         ):
             if len(peptide) == 0:
                 continue
diff --git a/casanovo/denovo/model_runner.py b/casanovo/denovo/model_runner.py
index fb5deeba..add48c93 100644
--- a/casanovo/denovo/model_runner.py
+++ b/casanovo/denovo/model_runner.py
@@ -14,6 +14,8 @@
 from depthcharge.data import AnnotatedSpectrumIndex, SpectrumIndex
 from pytorch_lightning.strategies import DDPStrategy
 
+from lightning.pytorch.accelerators import find_usable_cuda_devices
+
 from .. import utils
 from ..data import ms_io
 from ..denovo.dataloaders import DeNovoDataModule
@@ -96,8 +98,12 @@ def _execute_existing(
             model_filename,
         )
         raise FileNotFoundError("Could not find the trained model weights")
+    map_location = None
+    if torch.cuda.device_count() == 0:
+        map_location = "cpu"
     model = Spec2Pep().load_from_checkpoint(
         model_filename,
+        map_location=map_location,
         dim_model=config["dim_model"],
         n_head=config["n_head"],
         dim_feedforward=config["dim_feedforward"],
@@ -158,7 +164,6 @@ def _execute_existing(
     # Create the Trainer object.
     trainer = pl.Trainer(
         accelerator="auto",
-        auto_select_gpus=True,
         devices=_get_devices(config["no_gpu"]),
         logger=config["logger"],
         max_epochs=config["max_epochs"],
@@ -304,7 +309,6 @@ def train(
 
     trainer = pl.Trainer(
         accelerator="auto",
-        auto_select_gpus=True,
         callbacks=callbacks,
         devices=_get_devices(config["no_gpu"]),
         enable_checkpointing=config["save_model"],
@@ -352,7 +356,7 @@ def _get_peak_filenames(
     ]
 
 
-def _get_strategy() -> Optional[DDPStrategy]:
+def _get_strategy() -> Union[DDPStrategy, str]:
     """
     Get the strategy for the Trainer.
 
@@ -362,16 +366,16 @@ def _get_strategy() -> Optional[DDPStrategy]:
 
     Returns
     -------
-    Optional[DDPStrategy]
+    Union[DDPStrategy,str]
         The strategy parameter for the Trainer.
     """
     if torch.cuda.device_count() > 1:
         return DDPStrategy(find_unused_parameters=False, static_graph=True)
 
-    return None
+    return "auto"
 
 
-def _get_devices(no_gpu: bool) -> Union[int, str]:
+def _get_devices(no_gpu: bool) -> Union[List[int], str]:
     """
     Get the number of GPUs/CPUs for the Trainer to use.
 
@@ -382,16 +386,14 @@ def _get_devices(no_gpu: bool) -> Union[int, str]:
 
     Returns
     -------
-    Union[int, str]
-        The number of GPUs/CPUs to use, or "auto" to let PyTorch Lightning
-        determine the appropriate number of devices.
+    Union[List[int], str]
+        A list of CUDA GPU devices to use, or "auto" to let PyTorch Lightning determine
+        the appropriate number of devices.
     """
     if not no_gpu and any(
         operator.attrgetter(device + ".is_available")(torch)()
         for device in ("cuda",)
     ):
-        return -1
-    elif not (n_workers := utils.n_workers()):
-        return "auto"
+        return find_usable_cuda_devices()
     else:
-        return n_workers
+        return "auto"
diff --git a/pyproject.toml b/pyproject.toml
index db0fbe35..0ba22c32 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,7 +27,7 @@ dependencies = [
     "pandas",
     "psutil",
     "PyGithub",
-    "pytorch-lightning>=1.7,<2.0",
+    "lightning>=2.0.0",
     "PyYAML",
     "requests",
     "scikit-learn",