diff --git a/.github/workflows/linkcheck.yml b/.github/workflows/linkcheck.yml
new file mode 100644
index 0000000..4d39d1a
--- /dev/null
+++ b/.github/workflows/linkcheck.yml
@@ -0,0 +1,27 @@
+name: Check links
+on:
+  schedule:
+    - cron: '0 12 * * 3'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.10'
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt
+      - name: Check external links
+        run: make linkcheck
+        env:
+          SPHINXOPTS: --color
diff --git a/conf.py b/conf.py
index e1e0dcc..9537807 100644
--- a/conf.py
+++ b/conf.py
@@ -3,6 +3,8 @@
 # For the full list of built-in configuration values, see the documentation:
 # https://www.sphinx-doc.org/en/master/usage/configuration.html
 
+import sphinx
+
 # -- Project information -----------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
 
@@ -25,6 +27,9 @@
 templates_path = ['_templates']
 exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
 
+# User-Agent header sent with linkcheck HTTP requests.
+user_agent = f'Sphinx/{sphinx.__version__}'
+
 # Use ABNF syntax highlighting by default for code blocks.
 highlight_language = 'abnf'