diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 2f910d0..d7688bc 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,28 +1,35 @@
 # See https://pre-commit.com for more information
 # See https://pre-commit.com/hooks.html for more hooks
 repos:
--   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v4.3.0
-    hooks:
-    -   id: trailing-whitespace
-    -   id: end-of-file-fixer
-    -   id: check-yaml
-    -   id: check-added-large-files
--   repo: https://github.com/psf/black
-    rev: 22.3.0
-    hooks:
-    -   id: black
-        exclude: ^(fileformats/CHANGEME/_version\.py)$
-        args:
-          - -l 88
--   repo: https://github.com/codespell-project/codespell
-    rev: v2.1.0
-    hooks:
-    -   id: codespell
-        exclude: ^(fileformats/CHANGEME/_version\.py)$
-        args:
-        -   --ignore-words=.codespell-ignorewords
--   repo: https://github.com/PyCQA/flake8
-    rev: 4.0.1
-    hooks:
-    -   id: flake8
+    - repo: https://github.com/pre-commit/pre-commit-hooks
+      rev: v4.3.0
+      hooks:
+          - id: trailing-whitespace
+          - id: end-of-file-fixer
+          - id: check-yaml
+          - id: check-added-large-files
+    - repo: https://github.com/psf/black
+      rev: 22.3.0
+      hooks:
+          - id: black
+            exclude: ^(fileformats/CHANGEME/_version\.py)$
+            args:
+                - -l 88
+    - repo: https://github.com/codespell-project/codespell
+      rev: v2.1.0
+      hooks:
+          - id: codespell
+            exclude: ^(fileformats/CHANGEME/_version\.py)$
+            args:
+                - --ignore-words=.codespell-ignorewords
+    - repo: https://github.com/PyCQA/flake8
+      rev: 4.0.1
+      hooks:
+          - id: flake8
+    - repo: https://github.com/pre-commit/mirrors-mypy
+      rev: v1.11.2
+      hooks:
+          - id: mypy
+            args: [--strict, --install-types, --non-interactive]
+            exclude: tests
+            additional_dependencies: [pytest, fileformats]
diff --git a/conftest.py b/conftest.py
index 2a703c0..83aff9c 100644
--- a/conftest.py
+++ b/conftest.py
@@ -1,6 +1,7 @@
 import os
 import logging
 from pathlib import Path
+import typing as ty
 import tempfile
 import pytest
 
@@ -23,15 +24,16 @@
 if os.getenv("_PYTEST_RAISE", "0") != "0":
 
     @pytest.hookimpl(tryfirst=True)
-    def pytest_exception_interact(call):
-        raise call.excinfo.value
+    def pytest_exception_interact(call: pytest.CallInfo[ty.Any]) -> None:
+        if call.excinfo is not None:
+            raise call.excinfo.value
 
     @pytest.hookimpl(tryfirst=True)
-    def pytest_internalerror(excinfo):
+    def pytest_internalerror(excinfo: pytest.ExceptionInfo[BaseException]) -> None:
         raise excinfo.value
 
 
 @pytest.fixture
-def work_dir():
+def work_dir() -> Path:
     work_dir = tempfile.mkdtemp()
     return Path(work_dir)