diff --git a/pyproject.toml b/pyproject.toml
index 9787c3b..3fec353 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,6 @@
 [build-system]
 requires = ["setuptools", "wheel"]
 build-backend = "setuptools.build_meta"
+
+[tool.black]
+line-length = 120