diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c43f624..2be6680 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -3,22 +3,22 @@ name: ci
 on:
   push:
     branches:
-    - main
+      - main
   pull_request:
     branches:
-    - main
+      - main
 
 jobs:
   doc:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/setup-python@v2
-      with:
-        python-version: "3.x"
-    - uses: actions/checkout@v2
-    - run: |
-        pip install sphinx
-        sphinx-build -M html docs/ build/
+      - uses: actions/setup-python@v2
+        with:
+          python-version: "3.x"
+      - uses: actions/checkout@v2
+      - run: |
+          pip install sphinx
+          sphinx-build -M html docs/ build/
 
   lint:
     runs-on: ubuntu-latest
@@ -34,17 +34,18 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.7, 3.8, 3.9]
+        # vtk not available for 3.10 yet
+        python-version: ["3.7", "3.8", "3.9"]
     steps:
-    - uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-    - uses: actions/checkout@v2
-      with:
-        lfs: true
-    - name: Test with tox
-      run: |
-        pip install tox
-        tox -- --cov meshplex --cov-report xml --cov-report term
-    - uses: codecov/codecov-action@v1
-      if: ${{ matrix.python-version == '3.9' }}
+      - uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - uses: actions/checkout@v2
+        with:
+          lfs: true
+      - name: Test with tox
+        run: |
+          pip install tox
+          tox -- --cov meshplex --cov-report xml --cov-report term
+      - uses: codecov/codecov-action@v1
+        if: ${{ matrix.python-version == '3.9' }}
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index ddcbfd7..8fb20e7 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,16 +1,16 @@
 repos:
   - repo: https://github.com/PyCQA/isort
-    rev: 5.9.1
+    rev: 5.9.3
     hooks:
       - id: isort
 
-  - repo: https://github.com/python/black
-    rev: 21.6b0
+  - repo: https://github.com/psf/black
+    rev: 21.9b0
     hooks:
       - id: black
         language_version: python3
 
-  - repo: https://gitlab.com/pycqa/flake8
-    rev: 3.9.2
+  - repo: https://github.com/PyCQA/flake8
+    rev: 4.0.1
     hooks:
       - id: flake8
diff --git a/README.md b/README.md
index 77ec2f7..3f9600e 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,7 @@ meshplex is used in [optimesh](https://github.com/nschloe/optimesh) and
 ### Quickstart
 
 meshplex can compute the following data:
+
 ```python
 import meshplex
 
@@ -64,8 +65,11 @@ print(mesh.num_delaunay_violations)
 # removes some cells
 mesh.remove_cells([0])
 ```
+
 For triangular meshes (`MeshTri`), meshplex also has some mesh manipulation routines:
+
 <!--pytest-codeblocks:skip-->
+
 ```python
 mesh.show()  # show the mesh
 mesh.angles  # compute angles
@@ -81,9 +85,11 @@ For a documentation of all classes and functions, see
 ### Plotting
 
 #### Triangles
+
 <img src="https://nschloe.github.io/meshplex/pacman.png" width="30%">
 
 <!--pytest-codeblocks:skip-->
+
 ```python
 import meshplex
 
@@ -100,9 +106,11 @@ mesh.show(
 ```
 
 #### Tetrahedra
+
 <img src="https://nschloe.github.io/meshplex/tetra.png" width="30%">
 
 <!--pytest-codeblocks:skip-->
+
 ```python
 import numpy as np
 import meshplex
@@ -142,11 +150,14 @@ mesh.show_cell(
 
 meshplex is [available from the Python Package
 Index](https://pypi.org/project/meshplex/), so simply type
+
 ```
 pip install meshplex
 ```
+
 to install.
 
 ### License
+
 This software is published under the [GPLv3
 license](https://www.gnu.org/licenses/gpl-3.0.en.html).
diff --git a/docs/conf.py b/docs/conf.py
index 8d31af3..0942cf5 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -10,7 +10,8 @@
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 #
-import os
+import pathlib
+from configparser import ConfigParser
 
 # import sys
 # sys.path.insert(0, os.path.abspath('.'))
@@ -25,17 +26,11 @@
 copyright = "2017-2021, Nico Schlömer"
 author = "Nico Schlömer"
 
-#
-# https://packaging.python.org/guides/single-sourcing-package-version/
-this_dir = os.path.abspath(os.path.dirname(__file__))
-about = {}
-about_file = os.path.join(this_dir, "..", "src", "meshplex", "__about__.py")
-with open(about_file) as f:
-    exec(f.read(), about)
-# The short X.Y version.
-# version = ".".join(about["__version__"].split(".")[:2])
-# The full version, including alpha/beta/rc tags.
-release = about["__version__"]
+
+this_dir = pathlib.Path(__file__).resolve().parent
+p = ConfigParser()
+p.read(this_dir / ".." / "setup.cfg")
+release = p["metadata"]["version"]
 
 
 # -- General configuration ---------------------------------------------------
diff --git a/setup.cfg b/setup.cfg
index b2d8db2..5260bee 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,6 +1,6 @@
 [metadata]
 name = meshplex
-version = 0.16.5
+version = 0.16.6
 author = Nico Schlömer
 author_email = nico.schloemer@gmail.com
 description = Fast tools for simplex meshes
@@ -22,6 +22,7 @@ classifiers =
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
     Topic :: Scientific/Engineering
     Topic :: Scientific/Engineering :: Mathematics
 
@@ -30,9 +31,8 @@ package_dir =
     =src
 packages = find:
 install_requires =
-    importlib_metadata;python_version<"3.8"
     meshio >=4, <6
-    numpy >= 1.9
+    numpy >= 1.20.0
     npx >= 0.0.7
 python_requires = >=3.7
 
diff --git a/src/meshplex/__about__.py b/src/meshplex/__about__.py
deleted file mode 100644
index f85c205..0000000
--- a/src/meshplex/__about__.py
+++ /dev/null
@@ -1,10 +0,0 @@
-try:
-    # Python 3.8
-    from importlib import metadata
-except ImportError:
-    import importlib_metadata as metadata
-
-try:
-    __version__ = metadata.version("meshplex")
-except Exception:
-    __version__ = "unknown"
diff --git a/src/meshplex/__init__.py b/src/meshplex/__init__.py
index 8661e13..82f9c21 100644
--- a/src/meshplex/__init__.py
+++ b/src/meshplex/__init__.py
@@ -1,4 +1,3 @@
-from .__about__ import __version__
 from ._exceptions import MeshplexError
 from ._mesh import Mesh
 from ._mesh_tetra import MeshTetra
@@ -6,7 +5,6 @@
 from ._reader import from_meshio, read
 
 __all__ = [
-    "__version__",
     "Mesh",
     "MeshTri",
     "MeshTetra",
diff --git a/src/meshplex/_mesh.py b/src/meshplex/_mesh.py
index fa71509..66a88fb 100644
--- a/src/meshplex/_mesh.py
+++ b/src/meshplex/_mesh.py
@@ -116,7 +116,7 @@ def __repr__(self):
 
     # prevent overriding points without adapting the other mesh data
     @property
-    def points(self):
+    def points(self) -> np.ndarray:
         return self._points
 
     @points.setter
diff --git a/tests/test_io.py b/tests/test_io.py
index a170d7d..99acd28 100644
--- a/tests/test_io.py
+++ b/tests/test_io.py
@@ -7,7 +7,9 @@
 
 
 def test_io_2d():
-    vertices, cells = meshzoo.rectangle_tri((0.0, 0.0), (1.0, 1.0), 2)
+    vertices, cells = meshzoo.rectangle_tri(
+        np.linspace(0.0, 1.0, 3), np.linspace(0.0, 1.0, 3)
+    )
     mesh = meshplex.MeshTri(vertices, cells)
     # mesh = meshplex.read('pacman.vtu')
     assert mesh.num_delaunay_violations == 0
diff --git a/tox.ini b/tox.ini
index 3d9fbd3..fe4488f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@ isolated_build = True
 
 [testenv]
 deps =
-    meshzoo
+    meshzoo >= 0.9.0
     pytest
     pytest-cov
     pytest-codeblocks