diff --git a/.github/actions/commit-range/action.yml b/.github/actions/commit-range/action.yml
index 17eb5b647..7331dda2b 100644
--- a/.github/actions/commit-range/action.yml
+++ b/.github/actions/commit-range/action.yml
@@ -1,3 +1,4 @@
+---
 # Copyright (c) 2022, Eindhoven University of Technology - CST Robotics Group
 # BDS 3-Clause License (see ./LICENSE.md)
 
@@ -13,7 +14,8 @@ runs:
     - name: Commit range
       id: commit-range
       env:
-        commit_list: ${{ toJson(github.event.commits) }} # Doing this inside run doesn't work because of piping
+        # Doing this inside run doesn't work because of piping:
+        commit_list: ${{ toJson(github.event.commits) }}
       run: |
         if [ "${GITHUB_EVENT_NAME}" == "push" ]
         then
@@ -26,7 +28,9 @@ runs:
             NEWEST=$(echo "${commit_list}" | jq 'last.id' | tr -d '"')
             OLDEST_PARENTS=($(git show --no-patch --format="%P" ${OLDEST}))
             NUMBER_OLDEST_PARENTS=${#OLDEST_PARENTS[@]}
-            COMMIT_RANGE="${OLDEST}^${NUMBER_OLDEST_PARENTS}...${NEWEST}" # Take second parent if possible, see https://stackoverflow.com/a/2222920
+            # Take second parent if possible,
+            # see https://stackoverflow.com/a/2222920:
+            COMMIT_RANGE="${OLDEST}^${NUMBER_OLDEST_PARENTS}...${NEWEST}"
           fi
         elif [ "${GITHUB_EVENT_NAME}" == "pull_request" ]
         then
diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
index b3af0463c..b0b493dac 100644
--- a/.github/workflows/python-package.yml
+++ b/.github/workflows/python-package.yml
@@ -1,12 +1,13 @@
+---
 name: build
 
-on:
+on:  # yamllint disable-line rule:truthy
   push:
     branches:
-    - master
+      - master
   pull_request:
     branches:
-    - master
+      - master
 
 
 jobs:
@@ -17,22 +18,22 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - ubuntu-latest
-        - macos-latest
+          - ubuntu-latest
+          - macos-latest
     steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
-    - uses: cachix/install-nix-action@v16
-      with:
-        nix_path: nixpkgs=channel:nixos-21.11
-    - name: Run tests in nix-shell
-      run: |
-        nix-shell --pure --run '
-          python -m venv venv
-          venv/bin/pip install -e '.[isort,test]'
-          venv/bin/pytest
-        ' ./default.nix
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: cachix/install-nix-action@v16
+        with:
+          nix_path: nixpkgs=channel:nixos-21.11
+      - name: Run tests in nix-shell
+        run: |
+          nix-shell --pure --run '
+            python -m venv venv
+            venv/bin/pip install -e '.[isort,test]'
+            venv/bin/pytest
+          ' ./default.nix
 
   build:
 
@@ -41,37 +42,38 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - ubuntu-latest
-        - windows-latest
-        - macos-latest
+          - ubuntu-latest
+          - windows-latest
+          - macos-latest
         python-version:
-        - '3.6'
-        - '3.7'
-        - '3.8'
-        - '3.9'
-        - '3.10'
+          - '3.6'
+          - '3.7'
+          - '3.8'
+          - '3.9'
+          - '3.10'
         constraints: ['']
         include:
-        - os: ubuntu-latest
-          python-version: '3.7'
-          constraints: '--constraint constraints-oldest.txt'
-        - os: ubuntu-latest
-          python-version: '3.10'
-          constraints: '--constraint constraints-future.txt'
+          - os: ubuntu-latest
+            python-version: '3.7'
+            constraints: '--constraint constraints-oldest.txt'
+          - os: ubuntu-latest
+            python-version: '3.10'
+            constraints: '--constraint constraints-future.txt'
 
     steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
 
-    - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade 'pip>=20.3'  # strict dependency resolution added in pip 20.3
-        pip install -e '.[isort,test]' ${{ matrix.constraints }}
-    - name: Test with pytest
-      run: |
-        pytest
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          # strict dependency resolution added in pip 20.3
+          python -m pip install --upgrade 'pip>=20.3'
+          pip install -e '.[isort,test]' ${{ matrix.constraints }}
+      - name: Test with pytest
+        run: |
+          pytest
diff --git a/.github/workflows/test-future.yml b/.github/workflows/test-future.yml
index 84dc3afff..6458e1232 100644
--- a/.github/workflows/test-future.yml
+++ b/.github/workflows/test-future.yml
@@ -1,27 +1,29 @@
+---
 name: test-future
 
 # This workflow detects breakage against upcoming releases of dependencies
 # even in the absence of activity in Darker's own repository.
 
-on:
+on:  # yamllint disable-line rule:truthy
   schedule:
-  - cron: "05 20 * * 6"
+    - cron: "05 20 * * 6"
 
 jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
-      with:
-        ref: 'master'
-        fetch-depth: 0
-    - uses: actions/setup-python@v2
-      with:
-        python-version: '3.10'
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade 'pip>=20.3'  # strict dependency resolution added in pip 20.3
-        pip install -e '.[isort,test]' --constraint constraints-future.txt
-    - name: Test with pytest
-      run: |
-        pytest
+      - uses: actions/checkout@v2
+        with:
+          ref: 'master'
+          fetch-depth: 0
+      - uses: actions/setup-python@v2
+        with:
+          python-version: '3.10'
+      - name: Install dependencies
+        run: |
+          # strict dependency resolution added in pip 20.3
+          python -m pip install --upgrade 'pip>=20.3'
+          pip install -e '.[isort,test]' --constraint constraints-future.txt
+      - name: Test with pytest
+        run: |
+          pytest
diff --git a/.github/workflows/yaml-lint.yml b/.github/workflows/yaml-lint.yml
index 5b9db4683..2ec753fc8 100644
--- a/.github/workflows/yaml-lint.yml
+++ b/.github/workflows/yaml-lint.yml
@@ -1,3 +1,4 @@
+---
 name: Yaml Lint
 on: [push]  # yamllint disable-line rule:truthy
 jobs:
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a2a63dc99..f4b0f5dfe 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,22 +1,23 @@
+---
 # See https://pre-commit.com for more information
 repos:
--   repo: https://github.com/pre-commit/pre-commit-hooks
+  - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v3.3.0
     hooks:
-    -   id: trailing-whitespace
-    -   id: end-of-file-fixer
-    -   id: check-yaml
-    -   id: check-added-large-files
--   repo: https://github.com/akaihola/darker
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-added-large-files
+  - repo: https://github.com/akaihola/darker
     rev: master
     hooks:
-    -   id: darker
+      - id: darker
         args: [--isort]
         additional_dependencies:
           - black~=21.8b0
           - isort~=5.9
--   repo: https://github.com/Lucas-C/pre-commit-hooks-markup
+  - repo: https://github.com/Lucas-C/pre-commit-hooks-markup
     rev: v1.0.1
     hooks:
-    -   id: rst-linter
+      - id: rst-linter
         args: [--allow-raw]
diff --git a/.pre-commit-hooks.yaml b/.pre-commit-hooks.yaml
index 764295a63..99cd12320 100644
--- a/.pre-commit-hooks.yaml
+++ b/.pre-commit-hooks.yaml
@@ -1,6 +1,8 @@
+---
 - id: darker
   name: darker
-  description: "Black reformatting to Python files only in regions changed since last commit"
+  description: >-
+    Black reformatting to Python files only in regions changed since last commit
   entry: "darker -r :PRE-COMMIT:"
   language: python
   language_version: python3
diff --git a/.sourcery.yaml b/.sourcery.yaml
index 70a55eec9..dafc20def 100644
--- a/.sourcery.yaml
+++ b/.sourcery.yaml
@@ -1,2 +1,3 @@
+---
 ignore:
-  - 'test_*.py'  # parameterized tests would trigger Length and Working Memory detection
+  - 'test_*.py'  # parameterized tests trigger Length & Working Memory detection
diff --git a/action.yml b/action.yml
index 3c8b88477..c6849dfc3 100644
--- a/action.yml
+++ b/action.yml
@@ -1,11 +1,12 @@
+---
 name: "Darker"
 description: "Apply Black, isort and linters to modified lines only."
 author: "Antti Kaihola and contributors to Darker"
 inputs:
   options:
-    description:
-      "Options passed to Darker. Use `darker --help` to see available options. Default:
-      '--check --diff'"
+    description: >-
+      Options passed to Darker. Use `darker --help` to see available options.
+      Default: '--check --diff'
     required: false
     default: "--check --diff"
   src:
@@ -17,9 +18,9 @@ inputs:
     required: false
     default: "1.4.0"
   revision:
-    description:
-      'Git revision range to compare when determining modified lines. '
-      'Determined automatically if omitted.'
+    description: >-
+      Git revision range to compare when determining modified lines.
+      Determined automatically if omitted.
     required: false
 branding:
   color: "black"
@@ -54,7 +55,8 @@ runs:
           echo $entrypoint | python3
         fi
       env:
-        # TODO: Remove once https://github.com/actions/runner/issues/665 is fixed.
+        # TODO: Remove once https://github.com/actions/runner/issues/665 is
+        #       fixed.
         INPUT_OPTIONS: ${{ inputs.options }}
         INPUT_SRC: ${{ inputs.src }}
         INPUT_VERSION: ${{ inputs.version }}