diff --git a/.github/workflows/CI.yaml b/.github/workflows/CI.yaml
index 12bb2af0..605d1489 100644
--- a/.github/workflows/CI.yaml
+++ b/.github/workflows/CI.yaml
@@ -23,7 +23,8 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macOS-latest, ubuntu-latest, windows-latest]
+        # os: [macOS-latest, ubuntu-latest, windows-latest]      # TODO use this when macOS-latest becomes stable again
+        os: [macOS-13, ubuntu-latest, windows-latest]
         python-version: [3.8, 3.9, "3.10"]
 
     steps:
diff --git a/devtools/conda-envs/test_env.yaml b/devtools/conda-envs/test_env.yaml
index 1cc60519..831b4dbd 100644
--- a/devtools/conda-envs/test_env.yaml
+++ b/devtools/conda-envs/test_env.yaml
@@ -1,8 +1,8 @@
 name: test
 channels:
 
-  - conda-forge
   - pytorch
+  - conda-forge
 
   - defaults
 dependencies:
diff --git a/mlcolvar/data/datamodule.py b/mlcolvar/data/datamodule.py
index 613d600a..b0446d55 100644
--- a/mlcolvar/data/datamodule.py
+++ b/mlcolvar/data/datamodule.py
@@ -24,7 +24,6 @@
 import lightning
 from torch.utils.data import random_split, Subset
 from torch import default_generator, randperm
-from torch._utils import _accumulate
 
 from mlcolvar.data import DictLoader, DictDataset
 
@@ -324,6 +323,20 @@ def sequential_split(dataset, lengths: Sequence) -> list:
 
     return split_dataset(dataset=dataset, lengths=lengths, random_split=False)
 
+# Taken from python 3.5 docs, removed from PyTorch 2.3 onward
+def _accumulate(iterable, fn=lambda x, y: x + y):
+    "Return running totals"
+    # _accumulate([1,2,3,4,5]) --> 1 3 6 10 15
+    # _accumulate([1,2,3,4,5], operator.mul) --> 1 2 6 24 120
+    it = iter(iterable)
+    try:
+        total = next(it)
+    except StopIteration:
+        return
+    yield total
+    for element in it:
+        total = fn(total, element)
+        yield total
 
 if __name__ == "__main__":
     import doctest