diff --git a/pyproject.toml b/pyproject.toml
index 05efaf6b149aeed5b1405278ee0a20c6d9afb5d5..c37c26b577ebf1d2f68ab32eca393d1dad12252a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -57,6 +57,10 @@ pytest-sugar = "^0.9.2"
 [tool.poetry.plugins."aleksis.app"]
 alsijil = "aleksis.apps.alsijil.apps:AlsijilConfig"
 
+[tool.black]
+line-length = 100
+exclude = "/migrations/"
+
 [build-system]
 requires = ["poetry>=1.0"]
 build-backend = "poetry.masonry.api"