diff --git a/poetry.lock b/poetry.lock
index 41ae96c..1c16a1e 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -472,21 +472,6 @@ files = [
     {file = "roman_numerals-4.0.0.tar.gz", hash = "sha256:231287018a8788bf8c0718482a08c15b90458523ea1d840a18a791a86d4583b3"},
 ]
 
-[[package]]
-name = "roman-numerals-py"
-version = "4.0.0"
-description = "This package is deprecated, switch to roman-numerals."
-optional = false
-python-versions = ">=3.10"
-groups = ["main"]
-files = [
-    {file = "roman_numerals_py-4.0.0-py3-none-any.whl", hash = "sha256:dfcecf6e0cddbf2ee1112e7e2ebf58ba771984f075cb57a30e1811cee4f06332"},
-    {file = "roman_numerals_py-4.0.0.tar.gz", hash = "sha256:f7fa8dff5b7b7251d3a7586b97c57a0698e2e28898fa42c23bcc0cf51b02aee9"},
-]
-
-[package.dependencies]
-roman-numerals = "4.0.0"
-
 [[package]]
 name = "six"
 version = "1.17.0"
@@ -525,27 +510,27 @@ files = [
 
 [[package]]
 name = "sphinx"
-version = "8.2.3"
+version = "9.1.0"
 description = "Python documentation generator"
 optional = false
-python-versions = ">=3.11"
+python-versions = ">=3.12"
 groups = ["main"]
 files = [
-    {file = "sphinx-8.2.3-py3-none-any.whl", hash = "sha256:4405915165f13521d875a8c29c8970800a0141c14cc5416a38feca4ea5d9b9c3"},
-    {file = "sphinx-8.2.3.tar.gz", hash = "sha256:398ad29dee7f63a75888314e9424d40f52ce5a6a87ae88e7071e80af296ec348"},
+    {file = "sphinx-9.1.0-py3-none-any.whl", hash = "sha256:c84fdd4e782504495fe4f2c0b3413d6c2bf388589bb352d439b2a3bb99991978"},
+    {file = "sphinx-9.1.0.tar.gz", hash = "sha256:7741722357dd75f8190766926071fed3bdc211c74dd2d7d4df5404da95930ddb"},
 ]
 
 [package.dependencies]
 alabaster = ">=0.7.14"
 babel = ">=2.13"
 colorama = {version = ">=0.4.6", markers = "sys_platform == \"win32\""}
-docutils = ">=0.20,<0.22"
+docutils = ">=0.21,<0.23"
 imagesize = ">=1.3"
 Jinja2 = ">=3.1"
 packaging = ">=23.0"
 Pygments = ">=2.17"
 requests = ">=2.30.0"
-roman-numerals-py = ">=1.0.0"
+roman-numerals = ">=1.0.0"
 snowballstemmer = ">=2.2"
 sphinxcontrib-applehelp = ">=1.0.7"
 sphinxcontrib-devhelp = ">=1.0.6"
@@ -554,11 +539,6 @@ sphinxcontrib-jsmath = ">=1.0.1"
 sphinxcontrib-qthelp = ">=1.0.6"
 sphinxcontrib-serializinghtml = ">=1.1.9"
 
-[package.extras]
-docs = ["sphinxcontrib-websupport"]
-lint = ["betterproto (==2.0.0b6)", "mypy (==1.15.0)", "pypi-attestations (==0.0.21)", "pyright (==1.1.395)", "pytest (>=8.0)", "ruff (==0.9.9)", "sphinx-lint (>=0.9)", "types-Pillow (==10.2.0.20240822)", "types-Pygments (==2.19.0.20250219)", "types-colorama (==0.4.15.20240311)", "types-defusedxml (==0.7.0.20240218)", "types-docutils (==0.21.0.20241128)", "types-requests (==2.32.0.20241016)", "types-urllib3 (==1.26.25.14)"]
-test = ["cython (>=3.0)", "defusedxml (>=0.7.1)", "pytest (>=8.0)", "pytest-xdist[psutil] (>=3.4)", "setuptools (>=70.0)", "typing_extensions (>=4.9)"]
-
 [[package]]
 name = "sphinx-autobuild"
 version = "2025.8.25"
@@ -1036,4 +1016,4 @@ files = [
 [metadata]
 lock-version = "2.1"
 python-versions = "^3.12"
-content-hash = "3ed5e775594248ad00e582d59221b0599ba3d8af1a582dc2aab3471c0dcb50e4"
+content-hash = "bc501ab874a68b70ba959cbb95dda1ad55c3a9eeb9212164e9ddfc3c8e2e3054"
diff --git a/pyproject.toml b/pyproject.toml
index c83d2ef..26195a3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,7 +11,7 @@ package-mode = false
 
 [tool.poetry.dependencies]
 Python = "^3.12"
-sphinx = "^8"
+sphinx = ">=8,<10"
 sphinx-git = "^11"
 sphinxext-rediraffe = "^0.3.0"
 sphinx-last-updated-by-git = "^0.3.8"