diff --git a/pyproject.toml b/pyproject.toml
index b18a15c..c8014ea 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,12 +23,13 @@ mypy = "*"
 hypothesis = "*"
 flake8 = "*"
 pytest = "*"
+pytest-black = "*"
 pytest-cov = "*"
 pytest-flake8 = "*"
 pytest-mypy = "*"
 
 [tool.pytest.ini_options]
-addopts = "--cov=tornado_openapi3 --flake8 --mypy"
+addopts = "--cov=tornado_openapi3 --black --flake8 --mypy"
 
 [build-system]
 requires = ["poetry>=0.12"]
diff --git a/tox.ini b/tox.ini
index 9cfa834..5a3e8b3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,11 +7,13 @@ deps =
     tornado4: tornado>=4,<5
     tornado5: tornado>=5,<6
     tornado6: tornado>=6,<7
+    black
     codecov
     mypy
     hypothesis
     flake8
     pytest
+    pytest-black
     pytest-cov
     pytest-flake8
     pytest-mypy