diff --git a/setup.cfg b/setup.cfg
index 78a3083..c27ddc6 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -60,7 +60,7 @@ tests =
 pep8 = flake8
 coverage = pytest-cov
 docs =
-    sphinx
+    sphinx==8.1.1
     sphinx-rtd-theme
 release =
     bumpversion