diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..4dced2f
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,7 @@
+[tool.black]
+line-length = 120
+
+[tool.isort]
+profile = "black"
+multi_line_output = 3
+line_length = 120
diff --git a/tox.ini b/tox.ini
index 88df732..b50927c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,7 +10,7 @@ deps =
 skip_install = True
 commands =
     isort bdfr tests
-    black bdfr tests --line-length 120
+    black bdfr tests
 
 [testenv:format_check]
 deps =
@@ -20,10 +20,5 @@ skip_install = True
 allowlist_externals = mdl
 commands =
     isort bdfr tests --check
-    black bdfr tests --line-length 120 --check
+    black bdfr tests --check
     mdl README.md docs/ -s .markdown_style.rb
-
-[isort]
-profile = black
-multi_line_output = 3
-line_length = 120