diff --git a/pyproject.toml b/pyproject.toml
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,5 +1,6 @@
 [tool.black]
 target-version = ['py37']
+exclude = 'swh/web/tests/resources/contents'
 
 [tool.isort]
 multi_line_output = 3