diff --git a/pyproject.toml b/pyproject.toml
index 2a3f531..cdbc55a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -8,3 +8,6 @@ testpaths = [
 omit = [
     "*/tests/*",
 ]
+
+[tool.black]
+line-length = 99