diff --git a/pyproject.toml b/pyproject.toml
index cf464b2..0377ab5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -49,10 +49,10 @@ dev-flake8 = [
   "pydoclint == 0.8.3",
   "pydocstyle == 6.3.0",
 ]
-dev-formatting = ["black == 25.9.0", "isort == 8.0.1"]
+dev-formatting = ["black == 26.3.1", "isort == 8.0.1"]
 dev-mkdocs = [
   "Markdown == 3.10.2",
-  "black == 25.9.0",
+  "black == 26.3.1",
   "mike == 2.1.3",
   "mkdocs-gen-files == 0.6.1",
   "mkdocs-literate-nav == 0.6.3",
diff --git a/src/frequenz/quantities/__init__.py b/src/frequenz/quantities/__init__.py
index 6f30032..1afd324 100644
--- a/src/frequenz/quantities/__init__.py
+++ b/src/frequenz/quantities/__init__.py
@@ -86,7 +86,6 @@
 `pip install frequenz-quantities[marshmallow]`).
 """
 
-
 from ._apparent_power import ApparentPower
 from ._current import Current
 from ._energy import Energy
diff --git a/src/frequenz/quantities/_current.py b/src/frequenz/quantities/_current.py
index 62e5294..9c533d6 100644
--- a/src/frequenz/quantities/_current.py
+++ b/src/frequenz/quantities/_current.py
@@ -3,7 +3,6 @@
 
 """Types for holding quantities with units."""
 
-
 from __future__ import annotations
 
 from typing import TYPE_CHECKING, Self, overload
diff --git a/src/frequenz/quantities/_energy.py b/src/frequenz/quantities/_energy.py
index a0795e9..57d03f3 100644
--- a/src/frequenz/quantities/_energy.py
+++ b/src/frequenz/quantities/_energy.py
@@ -3,7 +3,6 @@
 
 """Types for holding quantities with units."""
 
-
 from __future__ import annotations
 
 from datetime import timedelta
diff --git a/src/frequenz/quantities/_frequency.py b/src/frequenz/quantities/_frequency.py
index 8c4d11c..ac17679 100644
--- a/src/frequenz/quantities/_frequency.py
+++ b/src/frequenz/quantities/_frequency.py
@@ -3,7 +3,6 @@
 
 """Types for holding quantities with units."""
 
-
 from datetime import timedelta
 from typing import Self
 
diff --git a/src/frequenz/quantities/_percentage.py b/src/frequenz/quantities/_percentage.py
index e0aa3c4..dcbb446 100644
--- a/src/frequenz/quantities/_percentage.py
+++ b/src/frequenz/quantities/_percentage.py
@@ -3,7 +3,6 @@
 
 """Types for holding quantities with units."""
 
-
 from typing import Self
 
 from ._quantity import NoDefaultConstructible, Quantity
diff --git a/src/frequenz/quantities/_power.py b/src/frequenz/quantities/_power.py
index 716682b..2feb2da 100644
--- a/src/frequenz/quantities/_power.py
+++ b/src/frequenz/quantities/_power.py
@@ -3,7 +3,6 @@
 
 """Types for holding quantities with units."""
 
-
 from __future__ import annotations
 
 from datetime import timedelta
diff --git a/src/frequenz/quantities/_quantity.py b/src/frequenz/quantities/_quantity.py
index 595ce46..db89c4a 100644
--- a/src/frequenz/quantities/_quantity.py
+++ b/src/frequenz/quantities/_quantity.py
@@ -3,7 +3,6 @@
 
 """Types for holding quantities with units."""
 
-
 from __future__ import annotations
 
 import math
diff --git a/src/frequenz/quantities/_reactive_power.py b/src/frequenz/quantities/_reactive_power.py
index 8a43f47..a38acd8 100644
--- a/src/frequenz/quantities/_reactive_power.py
+++ b/src/frequenz/quantities/_reactive_power.py
@@ -3,7 +3,6 @@
 
 """Types for holding reactive power quantities with units."""
 
-
 from __future__ import annotations
 
 from typing import TYPE_CHECKING, Self, overload
diff --git a/src/frequenz/quantities/_temperature.py b/src/frequenz/quantities/_temperature.py
index 361ad1f..6c20681 100644
--- a/src/frequenz/quantities/_temperature.py
+++ b/src/frequenz/quantities/_temperature.py
@@ -3,7 +3,6 @@
 
 """Types for holding quantities with units."""
 
-
 from typing import Self
 
 from ._quantity import NoDefaultConstructible, Quantity
diff --git a/src/frequenz/quantities/_voltage.py b/src/frequenz/quantities/_voltage.py
index ec6452a..412b2eb 100644
--- a/src/frequenz/quantities/_voltage.py
+++ b/src/frequenz/quantities/_voltage.py
@@ -3,7 +3,6 @@
 
 """Types for holding quantities with units."""
 
-
 from __future__ import annotations
 
 from typing import TYPE_CHECKING, Self, overload
diff --git a/tests/experimental/test_marshmallow.py b/tests/experimental/test_marshmallow.py
index 2b880e7..a285fa0 100644
--- a/tests/experimental/test_marshmallow.py
+++ b/tests/experimental/test_marshmallow.py
@@ -3,7 +3,6 @@
 
 """Test marshmallow fields and schema."""
 
-
 from dataclasses import dataclass, field
 from typing import Any, Self, cast