diff --git a/lib/spack/docs/requirements.txt b/lib/spack/docs/requirements.txt
index c9868afd197..82f20d8d1df 100644
--- a/lib/spack/docs/requirements.txt
+++ b/lib/spack/docs/requirements.txt
@@ -8,6 +8,6 @@ pygments==2.16.1
 urllib3==2.0.4
 pytest==7.4.2
 isort==5.12.0
-black==23.7.0
+black==23.9.1
 flake8==6.1.0
 mypy==1.5.1