diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index c820ab1..6651fc9 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -33,7 +33,7 @@ Install the project in editable mode:
 pip install -e .
 ```
 
-Install formatter, linter and test system: `pip install black~=21.4b0 flake8 mypy pytest pytest-cov`.
+Install formatter, linter and test system: `pip install black flake8 mypy pytest pytest-cov`.
 
 Be sure to enable Git hooks:
 
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 6fa008b..42962ac 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -18,7 +18,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install black~=21.4b0 flake8 pytest
+        pip install black flake8 pytest
         pip install -r requirements.txt
         pip install .
     - name: Check code style with Black
@@ -41,7 +41,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install black~=21.4b0 flake8 pytest
+        pip install black flake8 pytest
         pip install -r requirements.txt
         pip install .
     - name: Check code style with Black
diff --git a/doc/contributing.moi b/doc/contributing.moi
index 3fb155d..62951bd 100644
--- a/doc/contributing.moi
+++ b/doc/contributing.moi
@@ -30,7 +30,7 @@ Install the project in editable mode:
 
 \code {pip install -e .} {shell}
 
-Install formatter, linter and test system\: \m {pip install black~=21.4b0 flake8 mypy pytest pytest-cov}.
+Install formatter, linter and test system\: \m {pip install black flake8 mypy pytest pytest-cov}.
 
 Be sure to enable Git hooks:
 
diff --git a/map_machine/geometry/flinger.py b/map_machine/geometry/flinger.py
index b8f541a..5f0065c 100644
--- a/map_machine/geometry/flinger.py
+++ b/map_machine/geometry/flinger.py
@@ -38,7 +38,7 @@ def osm_zoom_level_to_pixels_per_meter(
         function allows any non-negative float value
     :param equator_length: celestial body equator length in meters
     """
-    return 2.0 ** zoom_level / equator_length * 256.0
+    return 2.0**zoom_level / equator_length * 256.0
 
 
 class Flinger:
@@ -56,7 +56,7 @@ class Flinger:
         :param equator_length: celestial body equator length in meters
         """
         self.geo_boundaries: BoundaryBox = geo_boundaries
-        self.ratio: float = 2.0 ** zoom_level * 256.0 / 360.0
+        self.ratio: float = 2.0**zoom_level * 256.0 / 360.0
         self.size: np.ndarray = self.ratio * (
             pseudo_mercator(self.geo_boundaries.max_())
             - pseudo_mercator(self.geo_boundaries.min_())
diff --git a/map_machine/slippy/tile.py b/map_machine/slippy/tile.py
index b9f2b20..36ec15a 100644
--- a/map_machine/slippy/tile.py
+++ b/map_machine/slippy/tile.py
@@ -55,7 +55,7 @@ class Tile:
         :param zoom_level: zoom level in OpenStreetMap terminology
         """
         lat_rad: np.ndarray = np.radians(coordinates[0])
-        scale: float = 2.0 ** zoom_level
+        scale: float = 2.0**zoom_level
         x: int = int((coordinates[1] + 180.0) / 360.0 * scale)
         y: int = int((1.0 - np.arcsinh(np.tan(lat_rad)) / np.pi) / 2.0 * scale)
         return cls(x, y, zoom_level)
@@ -66,7 +66,7 @@ class Tile:
 
         Code from https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
         """
-        scale: float = 2.0 ** self.zoom_level
+        scale: float = 2.0**self.zoom_level
         lon_deg: float = self.x / scale * 360.0 - 180.0
         lat_rad: float = np.arctan(np.sinh(np.pi * (1 - 2 * self.y / scale)))
         lat_deg: np.ndarray = np.degrees(lat_rad)