diff --git a/pyproject.toml b/pyproject.toml
index 42bb31eda..fa06458eb 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -45,4 +45,4 @@ omit = ["*/git/ext/*"]
 [tool.black]
 line-length = 120
 target-version = ['py37']
-exclude = "git/ext/gitdb"
+extend-exclude = "git/ext/gitdb"