diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a4922d6..7460332 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -31,6 +31,15 @@ repos:
             "-s",
           ]
 
+  - repo: local
+    hooks:
+      - id: pytest
+        name: Run unit tests
+        entry: bash -c 'uv run --group dev pytest tests/ -q; rc=$?; [ $rc -eq 5 ] && exit 0 || exit $rc'
+        language: system
+        types: [python]
+        pass_filenames: false
+
   - repo: https://github.com/python-jsonschema/check-jsonschema
     rev: 0.37.2
     hooks:
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..76677c9
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,9 @@
+[project]
+name = "rpmbuilder"
+version = "0.1.0"
+requires-python = ">=3.11"
+
+[dependency-groups]
+dev = [
+    "pytest>=8",
+]
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..fe2d9d4
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,2 @@
+# Tests for tools/build and tools/update-gh.
+# See https://git.unkin.net/unkin/rpmbuilder/issues/162