diff --git a/lib/spack/docs/requirements.txt b/lib/spack/docs/requirements.txt
index 279a910169b893..476b6b614d5062 100644
--- a/lib/spack/docs/requirements.txt
+++ b/lib/spack/docs/requirements.txt
@@ -11,6 +11,6 @@ pygments==2.19.2
 urllib3==2.5.0
 pytest==8.4.2
 isort==6.0.1
-black==25.1.0
+black==25.9.0
 flake8==7.3.0
 mypy==1.18.1