diff --git a/ORBIT/config.py b/ORBIT/config.py
index d97926d9..579cacd1 100644
--- a/ORBIT/config.py
+++ b/ORBIT/config.py
@@ -9,7 +9,9 @@
 from pathlib import Path
 
 import yaml
+import numpy as np
 from yaml import Dumper
+from benedict.dicts import benedict
 
 from ORBIT.core import loader
 
@@ -30,15 +32,47 @@ def load_config(filepath):
     return data
 
 
-def save_config(config, filepath, overwrite=False):
+def prepare_config_for_save(config: dict | benedict) -> dict:
+    """Prepare the configuration file for compatbility with the YAML
+    ``SafeDump`` class used for saving configurations to file.
+
+    Parameters
+    ----------
+    config : dict | benedict
+        ORBIT configuration dictionary.
+
+    Returns
+    -------
+    dict
+        ORBIT configuration dictionary where all NumPy data types are converted
+        to standard Python data types, e.g. ``np.float64`` -> ``float``.
     """
-    Save an ORBIT `config` to `filepath`.
+    for k, v in config.items():
+        match v:
+            case np.ndarray():
+                config[k] = v.tolist()
+            case np.floating():
+                config[k] = float(v)
+            case np.integer():
+                config[k] = int(v)
+            case dict():
+                config[k] = prepare_config_for_save(v)
+            case _:
+                pass
+    return config
+
+
+def save_config(
+    config: dict | benedict, filepath: str | Path, overwrite: bool = False
+):
+    """
+    Save an ORBIT configuration to :py:attr:`filepath`.
 
     Parameters
     ----------
-    config : dict
+    config : dict | benedict
         ORBIT configuration.
-    filepath : str
+    filepath : str | Path
         Location to save config.
     overwrite : bool (optional)
         Overwrite file if it already exists. Default: False.
@@ -53,5 +87,9 @@ def save_config(config, filepath, overwrite=False):
         if filepath.exists():
             raise FileExistsError(f"File already exists at '{filepath}'.")
 
+    config = prepare_config_for_save(config)
+    if isinstance(config, benedict):
+        config = config.dict()
+
     with filepath.open("w") as f:
         yaml.dump(config, f, Dumper=Dumper, default_flow_style=False)
diff --git a/pyproject.toml b/pyproject.toml
index 3a601972..c8fb3108 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -62,7 +62,7 @@ dev = [
   "pre-commit",
   "black",
   "isort",
-  "pytest",
+  "pytest>=9",
   "pytest-cov",
   "sphinx",
   "sphinx-rtd-theme",
diff --git a/tests/test_config_management.py b/tests/test_config_management.py
index 13a59cef..474ea81c 100644
--- a/tests/test_config_management.py
+++ b/tests/test_config_management.py
@@ -5,17 +5,26 @@
 
 
 from ORBIT import ProjectManager, load_config, save_config
+from ORBIT.config import prepare_config_for_save
 from ORBIT.core.library import extract_library_specs
 
-complete_project = extract_library_specs("config", "complete_project")
 
+def test_save_and_load_equality(subtests, tmp_yaml_del):
 
-def test_save_and_load_equality(tmp_yaml_del):
-
+    complete_project = extract_library_specs("config", "complete_project")
     save_config(complete_project, "tmp.yaml", overwrite=True)
     new = load_config("tmp.yaml")
 
-    assert new == complete_project
+    with subtests.test("Check direct file equality"):
+        assert new == complete_project
+
+    with subtests.test("Check ProjectManager equality"):
+        new_project = ProjectManager(new)
+        new = prepare_config_for_save(new_project.config)
+
+        expected_project = ProjectManager(complete_project)
+        complete_project = prepare_config_for_save(expected_project.config)
+        assert new == complete_project
 
 
 def test_orbit_version_ProjectManager():