diff --git a/poetry.lock b/poetry.lock
index 5275a0fa..213e516e 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -711,17 +711,17 @@ python-versions = "*"
 
 [[package]]
 name = "sphinx"
-version = "3.5.3"
+version = "4.1.1"
 description = "Python documentation generator"
 category = "dev"
 optional = false
-python-versions = ">=3.5"
+python-versions = ">=3.6"
 
 [package.dependencies]
 alabaster = ">=0.7,<0.8"
 babel = ">=1.3"
 colorama = {version = ">=0.3.5", markers = "sys_platform == \"win32\""}
-docutils = ">=0.12"
+docutils = ">=0.14,<0.18"
 imagesize = "*"
 Jinja2 = ">=2.3"
 packaging = "*"
@@ -730,14 +730,14 @@ requests = ">=2.5.0"
 snowballstemmer = ">=1.1"
 sphinxcontrib-applehelp = "*"
 sphinxcontrib-devhelp = "*"
-sphinxcontrib-htmlhelp = "*"
+sphinxcontrib-htmlhelp = ">=2.0.0"
 sphinxcontrib-jsmath = "*"
 sphinxcontrib-qthelp = "*"
-sphinxcontrib-serializinghtml = "*"
+sphinxcontrib-serializinghtml = ">=1.1.5"
 
 [package.extras]
 docs = ["sphinxcontrib-websupport"]
-lint = ["flake8 (>=3.5.0)", "isort", "mypy (>=0.800)", "docutils-stubs"]
+lint = ["flake8 (>=3.5.0)", "isort", "mypy (>=0.900)", "docutils-stubs", "types-typed-ast", "types-pkg-resources", "types-requests"]
 test = ["pytest", "pytest-cov", "html5lib", "cython", "typed-ast"]
 
 [[package]]
@@ -797,11 +797,11 @@ test = ["pytest"]
 
 [[package]]
 name = "sphinxcontrib-htmlhelp"
-version = "1.0.3"
+version = "2.0.0"
 description = "sphinxcontrib-htmlhelp is a sphinx extension which renders HTML help files"
 category = "dev"
 optional = false
-python-versions = ">=3.5"
+python-versions = ">=3.6"
 
 [package.extras]
 lint = ["flake8", "mypy", "docutils-stubs"]
@@ -832,7 +832,7 @@ test = ["pytest"]
 
 [[package]]
 name = "sphinxcontrib-serializinghtml"
-version = "1.1.4"
+version = "1.1.5"
 description = "sphinxcontrib-serializinghtml is a sphinx extension which outputs \"serialized\" HTML files (json and pickle)."
 category = "dev"
 optional = false
@@ -965,7 +965,7 @@ testing = ["pytest (>=3.5,!=3.7.3)", "pytest-checkdocs (>=1.2.3)", "pytest-flake
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.7.0"
-content-hash = "5cad4ed21ff84c53df1dd297b255b5f2f29a9fb446e1bbdb37fc51a11f5e6729"
+content-hash = "bd9c559ec7df37db5f1e662ec0e20d167afcd521eb1699d1609afef186d14f43"
 
 [metadata.files]
 alabaster = [
@@ -1429,8 +1429,8 @@ snowballstemmer = [
     {file = "snowballstemmer-2.0.0.tar.gz", hash = "sha256:df3bac3df4c2c01363f3dd2cfa78cce2840a79b9f1c2d2de9ce8d31683992f52"},
 ]
 sphinx = [
-    {file = "Sphinx-3.5.3-py3-none-any.whl", hash = "sha256:3f01732296465648da43dec8fb40dc451ba79eb3e2cc5c6d79005fd98197107d"},
-    {file = "Sphinx-3.5.3.tar.gz", hash = "sha256:ce9c228456131bab09a3d7d10ae58474de562a6f79abb3dc811ae401cf8c1abc"},
+    {file = "Sphinx-4.1.1-py3-none-any.whl", hash = "sha256:3d513088236eef51e5b0adb78b0492eb22cc3b8ccdb0b36dd021173b365d4454"},
+    {file = "Sphinx-4.1.1.tar.gz", hash = "sha256:23c846a1841af998cb736218539bb86d16f5eb95f5760b1966abcd2d584e62b8"},
 ]
 sphinx-autobuild = [
     {file = "sphinx-autobuild-2021.3.14.tar.gz", hash = "sha256:de1ca3b66e271d2b5b5140c35034c89e47f263f2cd5db302c9217065f7443f05"},
@@ -1449,8 +1449,8 @@ sphinxcontrib-devhelp = [
     {file = "sphinxcontrib_devhelp-1.0.2-py2.py3-none-any.whl", hash = "sha256:8165223f9a335cc1af7ffe1ed31d2871f325254c0423bc0c4c7cd1c1e4734a2e"},
 ]
 sphinxcontrib-htmlhelp = [
-    {file = "sphinxcontrib-htmlhelp-1.0.3.tar.gz", hash = "sha256:e8f5bb7e31b2dbb25b9cc435c8ab7a79787ebf7f906155729338f3156d93659b"},
-    {file = "sphinxcontrib_htmlhelp-1.0.3-py2.py3-none-any.whl", hash = "sha256:3c0bc24a2c41e340ac37c85ced6dafc879ab485c095b1d65d2461ac2f7cca86f"},
+    {file = "sphinxcontrib-htmlhelp-2.0.0.tar.gz", hash = "sha256:f5f8bb2d0d629f398bf47d0d69c07bc13b65f75a81ad9e2f71a63d4b7a2f6db2"},
+    {file = "sphinxcontrib_htmlhelp-2.0.0-py2.py3-none-any.whl", hash = "sha256:d412243dfb797ae3ec2b59eca0e52dac12e75a241bf0e4eb861e450d06c6ed07"},
 ]
 sphinxcontrib-jsmath = [
     {file = "sphinxcontrib-jsmath-1.0.1.tar.gz", hash = "sha256:a9925e4a4587247ed2191a22df5f6970656cb8ca2bd6284309578f2153e0c4b8"},
@@ -1461,8 +1461,8 @@ sphinxcontrib-qthelp = [
     {file = "sphinxcontrib_qthelp-1.0.3-py2.py3-none-any.whl", hash = "sha256:bd9fc24bcb748a8d51fd4ecaade681350aa63009a347a8c14e637895444dfab6"},
 ]
 sphinxcontrib-serializinghtml = [
-    {file = "sphinxcontrib-serializinghtml-1.1.4.tar.gz", hash = "sha256:eaa0eccc86e982a9b939b2b82d12cc5d013385ba5eadcc7e4fed23f4405f77bc"},
-    {file = "sphinxcontrib_serializinghtml-1.1.4-py2.py3-none-any.whl", hash = "sha256:f242a81d423f59617a8e5cf16f5d4d74e28ee9a66f9e5b637a18082991db5a9a"},
+    {file = "sphinxcontrib-serializinghtml-1.1.5.tar.gz", hash = "sha256:aa5f6de5dfdf809ef505c4895e51ef5c9eac17d0f287933eb49ec495280b6952"},
+    {file = "sphinxcontrib_serializinghtml-1.1.5-py2.py3-none-any.whl", hash = "sha256:352a9a00ae864471d3a7ead8d7d79f5fc0b57e8b3f95e9867eb9eb28999b92fd"},
 ]
 stevedore = [
     {file = "stevedore-3.2.2-py3-none-any.whl", hash = "sha256:5e1ab03eaae06ef6ce23859402de785f08d97780ed774948ef16c4652c41bc62"},
diff --git a/pyproject.toml b/pyproject.toml
index 1b0e290b..26b114be 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,7 +41,7 @@ safety = "^1.10.3"
 mypy = "^0.812"
 typeguard = "^2.12.1"
 xdoctest = {extras = ["colors"], version = "^0.15.0"}
-sphinx = "^3.5.3"
+sphinx = "^4.1.1"
 sphinx-autobuild = "^2021.3.14"
 pre-commit = "^2.11.1"
 flake8 = "^3.9.0"