diff --git a/pyproject.toml b/pyproject.toml
index cb0bf15f..95422a1d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -28,7 +28,7 @@ dependencies = ["pyyaml", "requests", "py", "importlib_resources~=6.3"]
 
 [project.optional-dependencies]
 test = ["coverage", "pytest"]
-doc = ["Sphinx~=6.2", "sphinx_rtd_theme~=1.3"]
+doc = ["Sphinx~=8.2", "sphinx_rtd_theme~=1.3"]
 
 [project.urls]
 Homepage = "https://github.com/dials/data"