diff --git a/pyproject.toml b/pyproject.toml
index d9217a5f..16cebe87 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -46,6 +46,7 @@ optional-dependencies.dev = [
     "deptry==0.20.0",
     "doc8==1.1.2",
     "doccmd==2024.10.8.12",
+    "docformatter==1.7.5",
     "interrogate==1.7.0",
     "mypy==1.11.2",
     "myst-parser==4.0.0",
@@ -67,7 +68,6 @@ optional-dependencies.dev = [
     "sphinx[test]==8.0.2",
     "types-docutils==0.21.0.20241005",
     "vulture==2.13",
-    "docformatter==1.7.5",
 ]
 optional-dependencies.release = [ "check-wheel-contents==0.6.0" ]
 urls.Source = "https://github.com/adamtheturtle/sphinx-substitution-extensions"
diff --git a/sample/source/__init__.py b/sample/source/__init__.py
index 535ceb2e..b63eed5f 100644
--- a/sample/source/__init__.py
+++ b/sample/source/__init__.py
@@ -1 +1,3 @@
-"""Documentation."""
+"""
+Documentation.
+"""
diff --git a/src/sphinx_substitution_extensions/__init__.py b/src/sphinx_substitution_extensions/__init__.py
index cac48371..240b4865 100644
--- a/src/sphinx_substitution_extensions/__init__.py
+++ b/src/sphinx_substitution_extensions/__init__.py
@@ -74,7 +74,9 @@ def run(self) -> list[Node]:
 
 @beartype
 class SubstitutionCodeRole:
-    """Custom role for substitution code."""
+    """
+    Custom role for substitution code.
+    """
 
     options: ClassVar[dict[str, Any]] = {
         "class": directives.class_option,
@@ -115,7 +117,9 @@ def __call__(  # pylint: disable=dangerous-default-value
 
 @beartype
 class SubstitutionXRefRole(XRefRole):
-    """Custom role for XRefs."""
+    """
+    Custom role for XRefs.
+    """
 
     def process_link(
         self,
diff --git a/tests/conftest.py b/tests/conftest.py
index 797fcf50..831e6e04 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,4 +1,6 @@
-"""Configuration for pytest."""
+"""
+Configuration for pytest.
+"""
 
 import pytest
 from beartype import beartype
diff --git a/tests/test_substitution_extensions.py b/tests/test_substitution_extensions.py
index 38554aa8..0941e38c 100644
--- a/tests/test_substitution_extensions.py
+++ b/tests/test_substitution_extensions.py
@@ -197,8 +197,7 @@ def test_substitution_download(
 ) -> None:
     """
     The ``substitution-download`` role replaces the placeholders defined in
-    ``conf.py`` as specified in both the download text and the download
-    target.
+    ``conf.py`` as specified in both the download text and the download target.
     """
     source_directory = tmp_path / "source"
     source_directory.mkdir()