diff --git a/mne_icalabel/annotation/bids.pyi b/mne_icalabel/annotation/bids.pyi
index 7910dacc..b52e9035 100644
--- a/mne_icalabel/annotation/bids.pyi
+++ b/mne_icalabel/annotation/bids.pyi
@@ -1,5 +1,4 @@
 from pathlib import Path as Path
-from typing import Union
 
 from mne.preprocessing import ICA
 
@@ -7,7 +6,7 @@ from ..config import ICA_LABELS_TO_MNE as ICA_LABELS_TO_MNE
 from ..iclabel._config import ICLABEL_STRING_TO_NUMERICAL as ICLABEL_STRING_TO_NUMERICAL
 from ..utils._imports import import_optional_dependency as import_optional_dependency
 
-def write_components_tsv(ica: ICA, fname: Union[str, Path]):
+def write_components_tsv(ica: ICA, fname: str | Path):
     """Write channels tsv file for ICA components.
 
     Will create an accompanying JSON sidecar to explain the
@@ -35,7 +34,7 @@ def write_components_tsv(ica: ICA, fname: Union[str, Path]):
 
 def mark_component(
     component: int,
-    fname: Union[str, Path],
+    fname: str | Path,
     method: str,
     label: str,
     author: str,
diff --git a/mne_icalabel/config.pyi b/mne_icalabel/config.pyi
index 7dd18c7c..42b5d55e 100644
--- a/mne_icalabel/config.pyi
+++ b/mne_icalabel/config.pyi
@@ -1,6 +1,6 @@
-from typing import Callable, Optional
+from typing import Callable
 
 from .iclabel import iclabel_label_components as iclabel_label_components
 
-ICALABEL_METHODS: dict[str, Optional[Callable]]
+ICALABEL_METHODS: dict[str, Callable | None]
 ICA_LABELS_TO_MNE: dict[str, str]
diff --git a/mne_icalabel/datasets/icalabel/icalabel.pyi b/mne_icalabel/datasets/icalabel/icalabel.pyi
index 7ce23dde..41d05233 100644
--- a/mne_icalabel/datasets/icalabel/icalabel.pyi
+++ b/mne_icalabel/datasets/icalabel/icalabel.pyi
@@ -1,12 +1,11 @@
 from pathlib import Path
-from typing import Optional
 
 from _typeshed import Incomplete
 
 has_icalabel_testing_data: Incomplete
 
 def data_path(
-    path: Optional[str] = None,
+    path: str | None = None,
     force_update: bool = False,
     update_path: bool = True,
     download: bool = True,
diff --git a/mne_icalabel/features/topomap.pyi b/mne_icalabel/features/topomap.pyi
index d373beaf..005f0128 100644
--- a/mne_icalabel/features/topomap.pyi
+++ b/mne_icalabel/features/topomap.pyi
@@ -1,5 +1,3 @@
-from typing import Union
-
 from _typeshed import Incomplete
 from mne import Info
 from mne.preprocessing import ICA
@@ -13,7 +11,7 @@ def get_topomaps(
     picks: Incomplete | None = None,
     res: int = 64,
     image_interp: str = ...,
-    border: Union[float, str] = ...,
+    border: float | str = ...,
     extrapolate: str = ...,
 ) -> dict[str, NDArray[float]]:
     """Generate an array of scalp topographies for the picked components.
@@ -64,7 +62,7 @@ def _get_topomap_array(
     info: Info,
     res: int = 64,
     image_interp: str = ...,
-    border: Union[float, str] = ...,
+    border: float | str = ...,
     extrapolate: str = ...,
 ) -> NDArray[float]:
     """Generate a scalp topographic map (n_pixels, n_pixels).
diff --git a/mne_icalabel/gui/_label_components.pyi b/mne_icalabel/gui/_label_components.pyi
index 1a906d7a..fedf4c16 100644
--- a/mne_icalabel/gui/_label_components.pyi
+++ b/mne_icalabel/gui/_label_components.pyi
@@ -1,5 +1,3 @@
-from typing import Union
-
 from _typeshed import Incomplete
 from mne import BaseEpochs
 from mne.io import BaseRaw
@@ -25,7 +23,7 @@ class ICAComponentLabeler(QMainWindow):
     _selected_component: int
 
     def __init__(
-        self, inst: Union[BaseRaw, BaseEpochs], ica: ICA, show: bool = True
+        self, inst: BaseRaw | BaseEpochs, ica: ICA, show: bool = True
     ) -> None: ...
     def _save_labels(self) -> None:
         """Save the selected labels to the ICA instance."""
@@ -56,11 +54,11 @@ class ICAComponentLabeler(QMainWindow):
         """
 
     @staticmethod
-    def _check_inst_ica(inst: Union[BaseRaw, BaseEpochs], ica: ICA) -> None:
+    def _check_inst_ica(inst: BaseRaw | BaseEpochs, ica: ICA) -> None:
         """Check if the ICA was fitted."""
 
     @property
-    def inst(self) -> Union[BaseRaw, BaseEpochs]:
+    def inst(self) -> BaseRaw | BaseEpochs:
         """Instance on which the ICA has been fitted."""
 
     @property
diff --git a/mne_icalabel/iclabel/features.pyi b/mne_icalabel/iclabel/features.pyi
index dba66dc7..044b52e0 100644
--- a/mne_icalabel/iclabel/features.pyi
+++ b/mne_icalabel/iclabel/features.pyi
@@ -1,5 +1,3 @@
-from typing import Union
-
 from mne import BaseEpochs
 from mne.io import BaseRaw
 from mne.preprocessing import ICA
@@ -11,7 +9,7 @@ from ._utils import _mne_to_eeglab_locs as _mne_to_eeglab_locs
 from ._utils import _next_power_of_2 as _next_power_of_2
 from ._utils import _pol2cart as _pol2cart
 
-def get_iclabel_features(inst: Union[BaseRaw, BaseEpochs], ica: ICA):
+def get_iclabel_features(inst: BaseRaw | BaseEpochs, ica: ICA):
     """Generate the features for ICLabel neural network.
 
     Parameters
@@ -52,9 +50,7 @@ def _retrieve_eeglab_icawinv(ica: ICA) -> tuple[NDArray[float], NDArray[float]]:
     weights : array
     """
 
-def _compute_ica_activations(
-    inst: Union[BaseRaw, BaseEpochs], ica: ICA
-) -> NDArray[float]:
+def _compute_ica_activations(inst: BaseRaw | BaseEpochs, ica: ICA) -> NDArray[float]:
     """Compute the ICA activations 'icaact' variable from an MNE ICA instance.
 
     Parameters
@@ -86,7 +82,7 @@ def _compute_ica_activations(
     """
 
 def _eeg_topoplot(
-    inst: Union[BaseRaw, BaseEpochs], icawinv: NDArray[float], picks: list[str]
+    inst: BaseRaw | BaseEpochs, icawinv: NDArray[float], picks: list[str]
 ) -> NDArray[float]:
     """Topoplot feature."""
 
@@ -96,17 +92,17 @@ def _topoplotFast(
     """Implement topoplotFast.m from MATLAB. Each topographic map is a 32x32 images."""
 
 def _eeg_rpsd(
-    inst: Union[BaseRaw, BaseEpochs], ica: ICA, icaact: NDArray[float]
+    inst: BaseRaw | BaseEpochs, ica: ICA, icaact: NDArray[float]
 ) -> NDArray[float]:
     """PSD feature."""
 
 def _eeg_rpsd_constants(
-    inst: Union[BaseRaw, BaseEpochs], ica: ICA
+    inst: BaseRaw | BaseEpochs, ica: ICA
 ) -> tuple[int, int, int, int, NDArray[int], NDArray[float], NDArray[int]]:
     """Compute the constants before ``randperm`` is used to compute the subset."""
 
 def _eeg_rpsd_compute_psdmed(
-    inst: Union[BaseRaw, BaseEpochs],
+    inst: BaseRaw | BaseEpochs,
     icaact: NDArray[float],
     ncomp: int,
     nfreqs: int,
@@ -143,7 +139,7 @@ def _eeg_autocorr_fftw(
     MATLAB: 'eeg_autocorr_fftw.m'.
     """
 
-def _resample(ac: NDArray[float], fs: Union[int, float]) -> NDArray[float]:
+def _resample(ac: NDArray[float], fs: int | float) -> NDArray[float]:
     """Resample the autocorrelation feature.
 
     The comment in EEGLAB is:
diff --git a/mne_icalabel/iclabel/label_components.pyi b/mne_icalabel/iclabel/label_components.pyi
index c8d7c4e9..c44b2807 100644
--- a/mne_icalabel/iclabel/label_components.pyi
+++ b/mne_icalabel/iclabel/label_components.pyi
@@ -1,5 +1,3 @@
-from typing import Optional, Union
-
 from mne import BaseEpochs as BaseEpochs
 from mne.io import BaseRaw as BaseRaw
 from mne.preprocessing import ICA
@@ -8,10 +6,10 @@ from .features import get_iclabel_features as get_iclabel_features
 from .network import run_iclabel as run_iclabel
 
 def iclabel_label_components(
-    inst: Union[BaseRaw, BaseEpochs],
+    inst: BaseRaw | BaseEpochs,
     ica: ICA,
     inplace: bool = True,
-    backend: Optional[str] = None,
+    backend: str | None = None,
 ):
     """Label the provided ICA components with the ICLabel neural network.
 
diff --git a/mne_icalabel/iclabel/network/__init__.pyi b/mne_icalabel/iclabel/network/__init__.pyi
index b8896342..bfde6007 100644
--- a/mne_icalabel/iclabel/network/__init__.pyi
+++ b/mne_icalabel/iclabel/network/__init__.pyi
@@ -1,12 +1,10 @@
-from typing import Optional
-
 from numpy.typing import ArrayLike, NDArray
 
 def run_iclabel(
     images: ArrayLike,
     psds: ArrayLike,
     autocorr: ArrayLike,
-    backend: Optional[str] = "pytorch",
+    backend: str | None = "pytorch",
 ) -> NDArray:
     """Run the ICLabel network on the provided set of features.
 
diff --git a/mne_icalabel/label_components.pyi b/mne_icalabel/label_components.pyi
index bcf1632e..beb49a34 100644
--- a/mne_icalabel/label_components.pyi
+++ b/mne_icalabel/label_components.pyi
@@ -1,5 +1,3 @@
-from typing import Union
-
 from mne import BaseEpochs as BaseEpochs
 from mne.io import BaseRaw as BaseRaw
 from mne.preprocessing import ICA
@@ -8,7 +6,7 @@ from .config import ICALABEL_METHODS as ICALABEL_METHODS
 from .iclabel._config import ICLABEL_NUMERICAL_TO_STRING as ICLABEL_NUMERICAL_TO_STRING
 from .utils._checks import _validate_inst_and_ica as _validate_inst_and_ica
 
-def label_components(inst: Union[BaseRaw, BaseEpochs], ica: ICA, method: str):
+def label_components(inst: BaseRaw | BaseEpochs, ica: ICA, method: str):
     """Automatically label the ICA components with the selected method.
 
     Parameters
diff --git a/mne_icalabel/utils/_checks.pyi b/mne_icalabel/utils/_checks.pyi
index 8c7d4826..29f36d47 100644
--- a/mne_icalabel/utils/_checks.pyi
+++ b/mne_icalabel/utils/_checks.pyi
@@ -1,10 +1,8 @@
-from typing import Union
-
 from mne import BaseEpochs
 from mne.io import BaseRaw
 from mne.preprocessing import ICA
 
-def _validate_inst_and_ica(inst: Union[BaseRaw, BaseEpochs], ica: ICA):
+def _validate_inst_and_ica(inst: BaseRaw | BaseEpochs, ica: ICA):
     """Make sure that the provided instance and ICA are valid."""
 
 def _validate_ica(ica: ICA):
diff --git a/mne_icalabel/utils/_imports.pyi b/mne_icalabel/utils/_imports.pyi
index a2b9c32a..0e087bca 100644
--- a/mne_icalabel/utils/_imports.pyi
+++ b/mne_icalabel/utils/_imports.pyi
@@ -1,11 +1,10 @@
 from types import ModuleType as ModuleType
-from typing import Optional
 
 _INSTALL_MAPPING: dict[str, str]
 
 def import_optional_dependency(
     name: str, extra: str = "", raise_error: bool = True
-) -> Optional[ModuleType]:
+) -> ModuleType | None:
     """Import an optional dependency.
 
     By default, if a dependency is missing an ImportError with a nice message will be
diff --git a/mne_icalabel/utils/config.pyi b/mne_icalabel/utils/config.pyi
index 895294b2..71dad22d 100644
--- a/mne_icalabel/utils/config.pyi
+++ b/mne_icalabel/utils/config.pyi
@@ -1,8 +1,8 @@
-from typing import IO, Callable, Optional
+from typing import IO, Callable
 
 from packaging.requirements import Requirement
 
-def sys_info(fid: Optional[IO] = None, developer: bool = False):
+def sys_info(fid: IO | None = None, developer: bool = False):
     """Print the system information for debugging.
 
     Parameters