diff --git a/python/damask/_colormap.py b/python/damask/_colormap.py
index 1f6e61b23..da59aaaad 100644
--- a/python/damask/_colormap.py
+++ b/python/damask/_colormap.py
@@ -2,7 +2,7 @@ import os
 import json
 import functools
 import colorsys
-from typing import Union, TextIO
+from typing import Optional, Union, TextIO
 from itertools import chain
 
 import numpy as np
@@ -275,8 +275,8 @@ class Colormap(mpl.colors.ListedColormap):
 
     def shade(self,
               field: np.ndarray,
-              bounds: FloatSequence = None,
-              gap: float = None) -> Image:
+              bounds: Optional[FloatSequence] = None,
+              gap: Optional[float] = None) -> Image:
         """
         Generate PIL image of 2D field using colormap.
 
@@ -315,7 +315,7 @@ class Colormap(mpl.colors.ListedColormap):
 
 
     def reversed(self,
-                 name: str = None) -> 'Colormap':
+                 name: Optional[str] = None) -> 'Colormap':
         """
         Reverse.
 
@@ -364,7 +364,7 @@ class Colormap(mpl.colors.ListedColormap):
 
 
     def save_paraview(self,
-                      fname: FileHandle = None):
+                      fname: Optional[FileHandle] = None):
         """
         Save as JSON file for use in Paraview.
 
@@ -388,7 +388,7 @@ class Colormap(mpl.colors.ListedColormap):
 
 
     def save_ASCII(self,
-                   fname: FileHandle = None):
+                   fname: Optional[FileHandle] = None):
         """
         Save as ASCII file.
 
@@ -403,7 +403,7 @@ class Colormap(mpl.colors.ListedColormap):
         t.save(self._get_file_handle(fname,'.txt'))
 
 
-    def save_GOM(self, fname: FileHandle = None):
+    def save_GOM(self, fname: Optional[FileHandle] = None):
         """
         Save as ASCII file for use in GOM Aramis.
 
@@ -424,7 +424,7 @@ class Colormap(mpl.colors.ListedColormap):
 
 
     def save_gmsh(self,
-                  fname: FileHandle = None):
+                  fname: Optional[FileHandle] = None):
         """
         Save as ASCII file for use in gmsh.
 
diff --git a/python/damask/_config.py b/python/damask/_config.py
index 5423699db..f6714cd81 100644
--- a/python/damask/_config.py
+++ b/python/damask/_config.py
@@ -2,7 +2,7 @@ import copy
 from io import StringIO
 from collections.abc import Iterable
 import abc
-from typing import Union, Dict, Any, Type, TypeVar
+from typing import Optional, Union, Dict, Any, Type, TypeVar
 
 import numpy as np
 import yaml
@@ -21,7 +21,7 @@ class NiceDumper(yaml.SafeDumper):
     """Make YAML readable for humans."""
 
     def write_line_break(self,
-                         data: str = None):
+                         data: Optional[str] = None):
         super().write_line_break(data)
 
         if len(self.indents) == 1:
@@ -53,7 +53,7 @@ class Config(dict):
     """YAML-based configuration."""
 
     def __init__(self,
-                 yml: Union[str, Dict[str, Any]] = None,
+                 yml: Union[None, str, Dict[str, Any]] = None,
                  **kwargs):
         """Initialize from YAML, dict, or key=value pairs."""
         if isinstance(yml,str):
diff --git a/python/damask/_configmaterial.py b/python/damask/_configmaterial.py
index d98f277fe..2c6ac4daa 100644
--- a/python/damask/_configmaterial.py
+++ b/python/damask/_configmaterial.py
@@ -1,6 +1,6 @@
 import numpy as np
 import h5py
-from typing import Union, Sequence, Dict, Any, Collection
+from typing import Optional, Union, Sequence, Dict, Any, Collection
 
 from ._typehints import FileHandle
 from . import Config
@@ -22,7 +22,7 @@ class ConfigMaterial(Config):
     """
 
     def __init__(self,
-                 d: Dict[str, Any] = None,
+                 d: Optional[Dict[str, Any]] = None,
                  **kwargs):
         """
         New material configuration.
@@ -83,13 +83,13 @@ class ConfigMaterial(Config):
 
     @staticmethod
     def load_DREAM3D(fname: str,
-                     grain_data: str = None,
-                     cell_data: str = None,
+                     grain_data: Optional[str] = None,
+                     cell_data: Optional[str] = None,
                      cell_ensemble_data: str = 'CellEnsembleData',
                      phases: str = 'Phases',
                      Euler_angles: str = 'EulerAngles',
                      phase_names: str = 'PhaseName',
-                     base_group: str = None) -> 'ConfigMaterial':
+                     base_group: Optional[str] = None) -> 'ConfigMaterial':
         """
         Load DREAM.3D (HDF5) file.
 
@@ -354,8 +354,8 @@ class ConfigMaterial(Config):
 
     def material_rename_phase(self,
                               mapping: Dict[str, str],
-                              ID: Sequence[int] = None,
-                              constituent: Sequence[int] = None) -> 'ConfigMaterial':
+                              ID: Optional[Sequence[int]] = None,
+                              constituent: Optional[Sequence[int]] = None) -> 'ConfigMaterial':
         """
         Change phase name in material.
 
@@ -388,7 +388,7 @@ class ConfigMaterial(Config):
 
     def material_rename_homogenization(self,
                                        mapping: Dict[str, str],
-                                       ID: Sequence[int] = None) -> 'ConfigMaterial':
+                                       ID: Optional[Sequence[int]] = None) -> 'ConfigMaterial':
         """
         Change homogenization name in material.
 
diff --git a/python/damask/_crystal.py b/python/damask/_crystal.py
index fb2dc3438..ed694fb12 100644
--- a/python/damask/_crystal.py
+++ b/python/damask/_crystal.py
@@ -1,4 +1,4 @@
-from typing import Union, Dict, List, Tuple
+from typing import Optional, Union, Dict, List, Tuple
 
 import numpy as np
 
@@ -324,10 +324,10 @@ class Crystal():
     """
 
     def __init__(self, *,
-                 family: CrystalFamily = None,
-                 lattice: CrystalLattice = None,
-                 a: float = None, b: float = None, c: float = None,
-                 alpha: float = None, beta: float = None, gamma: float = None,
+                 family: Optional[CrystalFamily] = None,
+                 lattice: Optional[CrystalLattice] = None,
+                 a: Optional[float] = None, b: Optional[float] = None, c: Optional[float] = None,
+                 alpha: Optional[float] = None, beta: Optional[float] = None, gamma: Optional[float] = None,
                  degrees: bool = False):
         """
         New representation of a crystal.
@@ -690,8 +690,8 @@ class Crystal():
                                               self.lattice[-1],None),dtype=float)
 
     def to_lattice(self, *,
-                   direction: FloatSequence = None,
-                   plane: FloatSequence = None) -> np.ndarray:
+                   direction: Optional[FloatSequence] = None,
+                   plane: Optional[FloatSequence] = None) -> np.ndarray:
         """
         Calculate lattice vector corresponding to crystal frame direction or plane normal.
 
@@ -717,8 +717,8 @@ class Crystal():
 
 
     def to_frame(self, *,
-                 uvw: FloatSequence = None,
-                 hkl: FloatSequence = None) -> np.ndarray:
+                 uvw: Optional[FloatSequence] = None,
+                 hkl: Optional[FloatSequence] = None) -> np.ndarray:
         """
         Calculate crystal frame vector corresponding to lattice direction [uvw] or plane normal (hkl).
 
diff --git a/python/damask/_grid.py b/python/damask/_grid.py
index 9197c1c5f..c73311482 100644
--- a/python/damask/_grid.py
+++ b/python/damask/_grid.py
@@ -4,7 +4,7 @@ import warnings
 import multiprocessing as mp
 from functools import partial
 import typing
-from typing import Union, Optional, TextIO, List, Sequence, Dict
+from typing import Optional, Union, TextIO, List, Sequence, Dict
 from pathlib import Path
 
 import numpy as np
@@ -34,8 +34,8 @@ class Grid:
                  material: np.ndarray,
                  size: FloatSequence,
                  origin: FloatSequence = np.zeros(3),
-                 initial_conditions: Dict[str,np.ndarray] = None,
-                 comments: Union[str, Sequence[str]] = None):
+                 initial_conditions: Optional[Dict[str,np.ndarray]] = None,
+                 comments: Union[None, str, Sequence[str]] = None):
         """
         New geometry definition for grid solvers.
 
@@ -348,9 +348,11 @@ class Grid:
 
     @staticmethod
     def load_DREAM3D(fname: Union[str, Path],
-                     feature_IDs: str = None, cell_data: str = None,
-                     phases: str = 'Phases', Euler_angles: str = 'EulerAngles',
-                     base_group: str = None) -> 'Grid':
+                     feature_IDs: Optional[str] = None,
+                     cell_data: Optional[str] = None,
+                     phases: str = 'Phases',
+                     Euler_angles: str = 'EulerAngles',
+                     base_group: Optional[str] = None) -> 'Grid':
         """
         Load DREAM.3D (HDF5) file.
 
@@ -463,7 +465,7 @@ class Grid:
                                    size: FloatSequence,
                                    seeds: np.ndarray,
                                    weights: FloatSequence,
-                                   material: IntSequence = None,
+                                   material: Optional[IntSequence] = None,
                                    periodic: bool = True):
         """
         Create grid from Laguerre tessellation.
@@ -520,7 +522,7 @@ class Grid:
     def from_Voronoi_tessellation(cells: IntSequence,
                                   size: FloatSequence,
                                   seeds: np.ndarray,
-                                  material: IntSequence = None,
+                                  material: Optional[IntSequence] = None,
                                   periodic: bool = True) -> 'Grid':
         """
         Create grid from Voronoi tessellation.
@@ -763,9 +765,9 @@ class Grid:
 
 
     def canvas(self,
-               cells: IntSequence = None,
-               offset: IntSequence = None,
-               fill: int = None) -> 'Grid':
+               cells: Optional[IntSequence] = None,
+               offset: Optional[IntSequence] = None,
+               fill: Optional[int] = None) -> 'Grid':
         """
         Crop or enlarge/pad grid.
 
@@ -901,7 +903,7 @@ class Grid:
 
     def rotate(self,
                R: Rotation,
-               fill: int = None) -> 'Grid':
+               fill: Optional[int] = None) -> 'Grid':
         """
         Rotate grid (and pad if required).
 
@@ -1093,10 +1095,10 @@ class Grid:
 
     def clean(self,
               distance: float = np.sqrt(3),
-              selection: IntCollection = None,
+              selection: Optional[IntCollection] = None,
               invert_selection: bool = False,
               periodic: bool = True,
-              rng_seed: NumpyRngSeed = None) -> 'Grid':
+              rng_seed: Optional[NumpyRngSeed] = None) -> 'Grid':
         """
         Smooth grid by selecting most frequent material ID within given stencil at each location.
 
@@ -1163,7 +1165,7 @@ class Grid:
                       dimension: Union[FloatSequence, IntSequence],
                       center: Union[FloatSequence, IntSequence],
                       exponent: Union[FloatSequence, float],
-                      fill: int = None,
+                      fill: Optional[int] = None,
                       R: Rotation = Rotation(),
                       inverse: bool = False,
                       periodic: bool = True) -> 'Grid':
@@ -1254,8 +1256,8 @@ class Grid:
 
     def vicinity_offset(self,
                         distance: float = np.sqrt(3),
-                        offset: int = None,
-                        selection: IntCollection = None,
+                        offset: Optional[int] = None,
+                        selection: Optional[IntCollection] = None,
                         invert_selection: bool = False,
                         periodic: bool = True) -> 'Grid':
         """
diff --git a/python/damask/_orientation.py b/python/damask/_orientation.py
index 95bcc6795..06eb6f3fc 100644
--- a/python/damask/_orientation.py
+++ b/python/damask/_orientation.py
@@ -1,6 +1,6 @@
 import inspect
 import copy
-from typing import Union, Callable, Dict, Any, Tuple, TypeVar
+from typing import Optional, Union, Callable, Dict, Any, Tuple, TypeVar
 
 import numpy as np
 
@@ -98,10 +98,10 @@ class Orientation(Rotation,Crystal):
     def __init__(self,
                  rotation: Union[FloatSequence, Rotation] = np.array([1.,0.,0.,0.]),
                  *,
-                 family: CrystalFamily = None,
-                 lattice: CrystalLattice = None,
-                 a: float = None, b: float = None, c: float = None,
-                 alpha: float = None, beta: float = None, gamma: float = None,
+                 family: Optional[CrystalFamily] = None,
+                 lattice: Optional[CrystalLattice] = None,
+                 a: Optional[float] = None, b: Optional[float] = None, c: Optional[float] = None,
+                 alpha: Optional[float] = None, beta: Optional[float] = None, gamma: Optional[float] = None,
                  degrees: bool = False):
         """
         New orientation.
@@ -131,7 +131,7 @@ class Orientation(Rotation,Crystal):
 
 
     def __copy__(self: MyType,
-                 rotation: Union[FloatSequence, Rotation] = None) -> MyType:
+                 rotation: Union[None, FloatSequence, Rotation] = None) -> MyType:
         """
         Return deepcopy(self).
 
@@ -617,7 +617,7 @@ class Orientation(Rotation,Crystal):
 
 
     def average(self,
-                weights: FloatSequence = None,
+                weights: Optional[FloatSequence] = None,
                 return_cloud: bool = False):
         """
         Return orientation average over last dimension.
@@ -819,8 +819,8 @@ class Orientation(Rotation,Crystal):
     # functions that require lattice, not just family
 
     def to_pole(self, *,
-                uvw: FloatSequence = None,
-                hkl: FloatSequence = None,
+                uvw: Optional[FloatSequence] = None,
+                hkl: Optional[FloatSequence] = None,
                 with_symmetry: bool = False,
                 normalize: bool = True) -> np.ndarray:
         """
@@ -861,8 +861,8 @@ class Orientation(Rotation,Crystal):
 
 
     def Schmid(self, *,
-               N_slip: IntSequence = None,
-               N_twin: IntSequence = None) -> np.ndarray:
+               N_slip: Optional[IntSequence] = None,
+               N_twin: Optional[IntSequence] = None) -> np.ndarray:
         u"""
         Calculate Schmid matrix P = d ⨂ n in the lab frame for selected deformation systems.
 
diff --git a/python/damask/_result.py b/python/damask/_result.py
index 7e19c66f7..2fa353f7d 100644
--- a/python/damask/_result.py
+++ b/python/damask/_result.py
@@ -11,7 +11,7 @@ from pathlib import Path
 from functools import partial
 from collections import defaultdict
 from collections.abc import Iterable
-from typing import Union, Callable, Any, Sequence, Literal, Dict, List, Tuple, Optional
+from typing import Optional, Union, Callable, Any, Sequence, Literal, Dict, List, Tuple
 
 import h5py
 import numpy as np
@@ -189,11 +189,11 @@ class Result:
 
     def _manage_view(self,
                      action: Literal['set', 'add', 'del'],
-                     increments: Union[int, Sequence[int], str, Sequence[str], bool] = None,
-                     times: Union[float, Sequence[float], str, Sequence[str], bool] = None,
-                     phases: Union[str, Sequence[str], bool] = None,
-                     homogenizations: Union[str, Sequence[str], bool] = None,
-                     fields: Union[str, Sequence[str], bool] = None) -> "Result":
+                     increments: Union[None, int, Sequence[int], str, Sequence[str], bool] = None,
+                     times: Union[None, float, Sequence[float], str, Sequence[str], bool] = None,
+                     phases: Union[None, str, Sequence[str], bool] = None,
+                     homogenizations: Union[None, str, Sequence[str], bool] = None,
+                     fields: Union[None, str, Sequence[str], bool] = None) -> "Result":
         """
         Manages the visibility of the groups.
 
@@ -256,8 +256,8 @@ class Result:
 
 
     def increments_in_range(self,
-                            start: Union[str, int] = None,
-                            end: Union[str, int] = None) -> Sequence[int]:
+                            start: Union[None, str, int] = None,
+                            end: Union[None, str, int] = None) -> Sequence[int]:
         """
         Get all increments within a given range.
 
@@ -280,8 +280,8 @@ class Result:
         return [i for i in self.incs if s <= i <= e]
 
     def times_in_range(self,
-                       start: float = None,
-                       end: float = None) -> Sequence[float]:
+                       start: Optional[float] = None,
+                       end: Optional[float] = None) -> Sequence[float]:
         """
         Get times of all increments within a given time range.
 
@@ -304,12 +304,12 @@ class Result:
 
 
     def view(self,*,
-             increments: Union[int, Sequence[int], str, Sequence[str], bool] = None,
-             times: Union[float, Sequence[float], str, Sequence[str], bool] = None,
-             phases: Union[str, Sequence[str], bool] = None,
-             homogenizations: Union[str, Sequence[str], bool] = None,
-             fields: Union[str, Sequence[str], bool] = None,
-             protected: bool = None) -> "Result":
+             increments: Union[None, int, Sequence[int], str, Sequence[str], bool] = None,
+             times: Union[None, float, Sequence[float], str, Sequence[str], bool] = None,
+             phases: Union[None, str, Sequence[str], bool] = None,
+             homogenizations: Union[None, str, Sequence[str], bool] = None,
+             fields: Union[None, str, Sequence[str], bool] = None,
+             protected: Optional[bool] = None) -> "Result":
         """
         Set view.
 
@@ -361,11 +361,11 @@ class Result:
 
 
     def view_more(self,*,
-                  increments: Union[int, Sequence[int], str, Sequence[str], bool] = None,
-                  times: Union[float, Sequence[float], str, Sequence[str], bool] = None,
-                  phases: Union[str, Sequence[str], bool] = None,
-                  homogenizations: Union[str, Sequence[str], bool] = None,
-                  fields: Union[str, Sequence[str], bool] = None) -> "Result":
+                  increments: Union[None, int, Sequence[int], str, Sequence[str], bool] = None,
+                  times: Union[None, float, Sequence[float], str, Sequence[str], bool] = None,
+                  phases: Union[None, str, Sequence[str], bool] = None,
+                  homogenizations: Union[None, str, Sequence[str], bool] = None,
+                  fields: Union[None, str, Sequence[str], bool] = None) -> "Result":
         """
         Add to view.
 
@@ -404,11 +404,11 @@ class Result:
 
 
     def view_less(self,*,
-                  increments: Union[int, Sequence[int], str, Sequence[str], bool] = None,
-                  times: Union[float, Sequence[float], str, Sequence[str], bool] = None,
-                  phases: Union[str, Sequence[str], bool] = None,
-                  homogenizations: Union[str, Sequence[str], bool] = None,
-                  fields: Union[str, Sequence[str], bool] = None) -> "Result":
+                  increments: Union[None, int, Sequence[int], str, Sequence[str], bool] = None,
+                  times: Union[None, float, Sequence[float], str, Sequence[str], bool] = None,
+                  phases: Union[None, str, Sequence[str], bool] = None,
+                  homogenizations: Union[None, str, Sequence[str], bool] = None,
+                  fields: Union[None, str, Sequence[str], bool] = None) -> "Result":
         """
         Remove from view.
 
@@ -650,7 +650,7 @@ class Result:
                         formula: str,
                         name: str,
                         unit: str = 'n/a',
-                        description: str = None):
+                        description: Optional[str] = None):
         """
         Add result of a general formula.
 
@@ -966,7 +966,7 @@ class Result:
                 }
     def add_equivalent_Mises(self,
                              T_sym: str,
-                             kind: str = None):
+                             kind: Optional[str] = None):
         """
         Add the equivalent Mises stress or strain of a symmetric tensor.
 
@@ -1021,7 +1021,7 @@ class Result:
                  }
     def add_norm(self,
                  x: str,
-                 ord: Union[int, float, Literal['fro', 'nuc']] = None):
+                 ord: Union[None, int, float, Literal['fro', 'nuc']] = None):
         """
         Add the norm of vector or tensor.
 
@@ -1101,8 +1101,8 @@ class Result:
     def add_pole(self,
                  q: str = 'O',
                  *,
-                 uvw: FloatSequence = None,
-                 hkl: FloatSequence = None,
+                 uvw: Optional[FloatSequence] = None,
+                 hkl: Optional[FloatSequence] = None,
                  with_symmetry: bool = False,
                  normalize: bool = True):
         """
@@ -1593,7 +1593,7 @@ class Result:
               output: Union[str, List[str]] = '*',
               flatten: bool = True,
               prune: bool = True,
-              constituents: IntSequence = None,
+              constituents: Optional[IntSequence] = None,
               fill_float: float = np.nan,
               fill_int: int = 0) -> Optional[Dict[str,Any]]:
         """
@@ -1683,7 +1683,7 @@ class Result:
 
     def export_XDMF(self,
                     output: Union[str, List[str]] = '*',
-                    target_dir: Union[str, Path] = None,
+                    target_dir: Union[None, str, Path] = None,
                     absolute_path: bool = False):
         """
         Write XDMF file to directly visualize data from DADF5 file.
@@ -1811,8 +1811,8 @@ class Result:
     def export_VTK(self,
                    output: Union[str,List[str]] = '*',
                    mode: str = 'cell',
-                   constituents: IntSequence = None,
-                   target_dir: Union[str, Path] = None,
+                   constituents: Optional[IntSequence] = None,
+                   target_dir: Union[None, str, Path] = None,
                    fill_float: float = np.nan,
                    fill_int: int = 0,
                    parallel: bool = True):
@@ -1958,7 +1958,7 @@ class Result:
 
     def export_simulation_setup(self,
                      output: Union[str, List[str]] = '*',
-                     target_dir: Union[str, Path] = None,
+                     target_dir: Union[None, str, Path] = None,
                      overwrite: bool = False,
                      ):
         """
diff --git a/python/damask/_rotation.py b/python/damask/_rotation.py
index 07eb25803..567c91d37 100644
--- a/python/damask/_rotation.py
+++ b/python/damask/_rotation.py
@@ -1,5 +1,5 @@
 import copy
-from typing import Union, Sequence, Tuple, Literal, List, TypeVar
+from typing import Optional, Union, Sequence, Tuple, Literal, List, TypeVar
 
 import numpy as np
 
@@ -99,7 +99,7 @@ class Rotation:
 
 
     def __copy__(self: MyType,
-                 rotation: Union[FloatSequence, 'Rotation'] = None) -> MyType:
+                 rotation: Union[None, FloatSequence, 'Rotation'] = None) -> MyType:
         """
         Return deepcopy(self).
 
@@ -514,7 +514,7 @@ class Rotation:
 
 
     def average(self: MyType,
-                weights: FloatSequence = None) -> MyType:
+                weights: Optional[FloatSequence] = None) -> MyType:
         """
         Average along last array dimension.
 
@@ -1044,8 +1044,8 @@ class Rotation:
 
 
     @staticmethod
-    def from_random(shape: Union[int, IntSequence] = None,
-                    rng_seed: NumpyRngSeed = None) -> 'Rotation':
+    def from_random(shape: Union[None, int, IntSequence] = None,
+                    rng_seed: Optional[NumpyRngSeed] = None) -> 'Rotation':
         """
         Initialize with samples from a uniform distribution.
 
@@ -1078,10 +1078,10 @@ class Rotation:
     @staticmethod
     def from_ODF(weights: np.ndarray,
                  phi: np.ndarray,
-                 shape: Union[int, IntSequence] = None,
+                 shape: Union[None, int, IntSequence] = None,
                  degrees: bool = False,
                  fractions: bool = True,
-                 rng_seed: NumpyRngSeed = None) -> 'Rotation':
+                 rng_seed: Optional[NumpyRngSeed] = None) -> 'Rotation':
         """
         Initialize with samples from a binned orientation distribution function (ODF).
 
@@ -1135,9 +1135,9 @@ class Rotation:
     @staticmethod
     def from_spherical_component(center: 'Rotation',
                                  sigma: float,
-                                 shape: Union[int, IntSequence] = None,
+                                 shape: Union[None, int, IntSequence] = None,
                                  degrees: bool = False,
-                                 rng_seed: NumpyRngSeed = None) -> 'Rotation':
+                                 rng_seed: Optional[NumpyRngSeed] = None) -> 'Rotation':
         """
         Initialize with samples from a Gaussian distribution around a given center.
 
@@ -1188,9 +1188,9 @@ class Rotation:
     def from_fiber_component(crystal: IntSequence,
                              sample: IntSequence,
                              sigma: float = 0.,
-                             shape: Union[int, IntSequence] = None,
+                             shape: Union[None, int, IntSequence] = None,
                              degrees: bool = False,
-                             rng_seed: NumpyRngSeed = None) -> 'Rotation':
+                             rng_seed: Optional[NumpyRngSeed] = None) -> 'Rotation':
         """
         Initialize with samples from a Gaussian distribution around a given direction.
 
diff --git a/python/damask/_table.py b/python/damask/_table.py
index 990568364..9aa0a8ce5 100644
--- a/python/damask/_table.py
+++ b/python/damask/_table.py
@@ -1,6 +1,6 @@
 import re
 import copy
-from typing import Union, Tuple, List, Iterable
+from typing import Optional, Union, Tuple, List, Iterable
 
 import pandas as pd
 import numpy as np
@@ -13,8 +13,8 @@ class Table:
 
     def __init__(self,
                  shapes: dict = {},
-                 data: np.ndarray = None,
-                 comments: Union[str, Iterable[str]] = None):
+                 data: Optional[np.ndarray] = None,
+                 comments: Union[None, str, Iterable[str]] = None):
         """
         New spreadsheet.
 
@@ -188,7 +188,7 @@ class Table:
     def _add_comment(self,
                      label: str,
                      shape: Tuple[int, ...],
-                     info: str = None):
+                     info: Optional[str] = None):
         if info is not None:
             specific = f'{label}{" "+str(shape) if np.prod(shape,dtype=np.int64) > 1 else ""}: {info}'
             general  = util.execution_stamp('Table')
@@ -383,7 +383,7 @@ class Table:
     def set(self,
             label: str,
             data: np.ndarray,
-            info: str = None) -> 'Table':
+            info: Optional[str] = None) -> 'Table':
         """
         Add new or replace existing column data.
 
@@ -458,7 +458,7 @@ class Table:
     def rename(self,
                old: Union[str, Iterable[str]],
                new: Union[str, Iterable[str]],
-               info: str = None) -> 'Table':
+               info: Optional[str] = None) -> 'Table':
         """
         Rename column data.
 
diff --git a/python/damask/_vtk.py b/python/damask/_vtk.py
index dede9f374..e398c0d53 100644
--- a/python/damask/_vtk.py
+++ b/python/damask/_vtk.py
@@ -1,7 +1,7 @@
 import os
 import multiprocessing as mp
 from pathlib import Path
-from typing import Union, Literal, List, Sequence
+from typing import Optional, Union, Literal, List, Sequence
 
 import numpy as np
 import vtk
@@ -286,7 +286,7 @@ class VTK:
 
     @staticmethod
     def load(fname: Union[str, Path],
-             dataset_type: Literal['ImageData', 'UnstructuredGrid', 'PolyData', 'RectilinearGrid'] = None) -> 'VTK':
+             dataset_type: Literal[None, 'ImageData', 'UnstructuredGrid', 'PolyData', 'RectilinearGrid'] = None) -> 'VTK':
         """
         Load from VTK file.
 
@@ -409,11 +409,11 @@ class VTK:
 
     # Check https://blog.kitware.com/ghost-and-blanking-visibility-changes/ for missing data
     def set(self,
-            label: str = None,
-            data: Union[np.ndarray, np.ma.MaskedArray] = None,
-            info: str = None,
+            label: Optional[str] = None,
+            data: Union[None, np.ndarray, np.ma.MaskedArray] = None,
+            info: Optional[str] = None,
             *,
-            table: 'Table' = None):
+            table: Optional['Table'] = None):
         """
         Add new or replace existing point or cell data.
 
@@ -533,7 +533,7 @@ class VTK:
 
 
     def show(self,
-             label: str = None,
+             label: Optional[str] = None,
              colormap: Union[Colormap, str] = 'cividis'):
         """
         Render.
diff --git a/python/damask/seeds.py b/python/damask/seeds.py
index 7cea9d51c..4ea4afaad 100644
--- a/python/damask/seeds.py
+++ b/python/damask/seeds.py
@@ -1,6 +1,6 @@
 """Functionality for generation of seed points for Voronoi or Laguerre tessellation."""
 
-from typing import Tuple as _Tuple
+from typing import Optional as _Optional, Tuple as _Tuple
 
 from scipy import spatial as _spatial
 import numpy as _np
@@ -13,8 +13,8 @@ from . import grid_filters as _grid_filters
 
 def from_random(size: _FloatSequence,
                 N_seeds: int,
-                cells: _IntSequence = None,
-                rng_seed: _NumpyRngSeed = None) -> _np.ndarray:
+                cells: _Optional[_IntSequence] = None,
+                rng_seed: _Optional[_NumpyRngSeed] = None) -> _np.ndarray:
     """
     Place seeds randomly in space.
 
@@ -54,7 +54,7 @@ def from_Poisson_disc(size: _FloatSequence,
                       N_candidates: int,
                       distance: float,
                       periodic: bool = True,
-                      rng_seed: _NumpyRngSeed = None) -> _np.ndarray:
+                      rng_seed: _Optional[_NumpyRngSeed] = None) -> _np.ndarray:
     """
     Place seeds according to a Poisson disc distribution.
 
@@ -106,7 +106,7 @@ def from_Poisson_disc(size: _FloatSequence,
 
 
 def from_grid(grid,
-              selection: _IntCollection = None,
+              selection: _Optional[_IntCollection] = None,
               invert_selection: bool = False,
               average: bool = False,
               periodic: bool = True) -> _Tuple[_np.ndarray, _np.ndarray]:
diff --git a/python/damask/util.py b/python/damask/util.py
index c23d3c802..16054b6cb 100644
--- a/python/damask/util.py
+++ b/python/damask/util.py
@@ -10,8 +10,9 @@ import signal as _signal
 import fractions as _fractions
 from collections import abc as _abc
 from functools import reduce as _reduce, partial as _partial
-from typing import Callable as _Callable, Union as _Union, Iterable as _Iterable, Sequence as _Sequence, Dict as _Dict,  \
-                   List as _List, Tuple as _Tuple, Literal as _Literal, Any as _Any, Collection as _Collection, TextIO as _TextIO
+from typing import Optional as _Optional, Callable as _Callable, Union as _Union, Iterable as _Iterable, \
+                   Sequence as _Sequence, Dict as _Dict, List as _List, Tuple as _Tuple, Literal as _Literal, \
+                   Any as _Any, Collection as _Collection, TextIO as _TextIO
 from pathlib import Path as _Path
 
 import numpy as _np
@@ -140,8 +141,8 @@ def strikeout(msg) -> str:
 
 def run(cmd: str,
         wd: str = './',
-        env: _Dict[str, str] = None,
-        timeout: int = None) -> _Tuple[str, str]:
+        env: _Optional[_Dict[str, str]] = None,
+        timeout: _Optional[int] = None) -> _Tuple[str, str]:
     """
     Run a command.
 
@@ -215,7 +216,7 @@ def open_text(fname: _FileHandle,
 
 
 def execution_stamp(class_name: str,
-                    function_name: str = None) -> str:
+                    function_name: _Optional[str] = None) -> str:
     """Timestamp the execution of a (function within a) class."""
     now = _datetime.datetime.now().astimezone().strftime('%Y-%m-%d %H:%M:%S%z')
     _function_name = '' if function_name is None else f'.{function_name}'
@@ -238,7 +239,7 @@ def natural_sort(key: str) -> _List[_Union[int, str]]:
 
 
 def show_progress(iterable: _Iterable,
-                  N_iter: int = None,
+                  N_iter: _Optional[int] = None,
                   prefix: str = '',
                   bar_length: int = 50) -> _Any:
     """
@@ -418,7 +419,7 @@ def project_equal_area(vector: _np.ndarray,
 
 def hybrid_IA(dist: _FloatSequence,
               N: int,
-              rng_seed: _NumpyRngSeed = None) -> _np.ndarray:
+              rng_seed: _Optional[_NumpyRngSeed] = None) -> _np.ndarray:
     """
     Hybrid integer approximation.
 
@@ -540,10 +541,10 @@ def shapeblender(a: _Tuple[int, ...],
 
 
 def _docstringer(docstring: _Union[str, _Callable],
-                 extra_parameters: str = None,
-                 # extra_examples: str = None,
-                 # extra_notes: str = None,
-                 return_type: _Union[str, _Callable] = None) -> str:
+                 extra_parameters: _Optional[str] = None,
+                 # extra_examples: _Optional[str] = None,
+                 # extra_notes: _Optional[str] = None,
+                 return_type: _Union[None, str, _Callable] = None) -> str:
     """
     Extend a docstring.
 
@@ -593,8 +594,8 @@ def _docstringer(docstring: _Union[str, _Callable],
                            fr'\1{return_type_}\n',
                            docstring_,flags=_re.MULTILINE)
 
-def extend_docstring(docstring: _Union[str, _Callable] = None,
-                     extra_parameters: str = None) -> _Callable:
+def extend_docstring(docstring: _Union[None, str, _Callable] = None,
+                     extra_parameters: _Optional[str] = None) -> _Callable:
     """
     Decorator: Extend the function's docstring.
 
@@ -678,8 +679,8 @@ def DREAM3D_cell_data_group(fname: _Union[str, _Path]) -> str:
 
 
 def Bravais_to_Miller(*,
-                      uvtw: _np.ndarray = None,
-                      hkil: _np.ndarray = None) -> _np.ndarray:
+                      uvtw: _Optional[_np.ndarray] = None,
+                      hkil: _Optional[_np.ndarray] = None) -> _np.ndarray:
     """
     Transform 4 Miller–Bravais indices to 3 Miller indices of crystal direction [uvw] or plane normal (hkl).
 
@@ -706,8 +707,8 @@ def Bravais_to_Miller(*,
     return _np.einsum('il,...l',basis,axis)
 
 def Miller_to_Bravais(*,
-                      uvw: _np.ndarray = None,
-                      hkl: _np.ndarray = None) -> _np.ndarray:
+                      uvw: _Optional[_np.ndarray] = None,
+                      hkl: _Optional[_np.ndarray] = None) -> _np.ndarray:
     """
     Transform 3 Miller indices to 4 Miller–Bravais indices of crystal direction [uvtw] or plane normal (hkil).