diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index b68607dc4200be2942b5ccb7db96e965718d85fc..8dd5324fd7c0c1ca5207c86f69329ea1a7e15a61 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -128,6 +128,7 @@ licence possible.
 
 .. _PEP 8: https://pep8.org/
 .. _Django coding style: https://docs.djangoproject.com/en/dev/internals/contributing/writing-code/coding-style/
+.. _black: https://black.readthedocs.io/en/stable/
 .. _Django Best Practices: https://django-best-practices.readthedocs.io/en/latest/index.html
 .. _How to Write a Git Commit Message: https://chris.beams.io/posts/git-commit/
 .. _Sane software manifesto: https://sane-software.globalcode.info/