diff --git a/pyproject.toml b/pyproject.toml
index 078e04b..fcdf16e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,7 +18,7 @@ classifiers = ["License :: OSI Approved :: Apache Software License"]
 license = { file = "LICENSE" }
 
 [project.optional-dependencies]
-docs = ["toml~=0.10.2", "sphinx>=5,<9", "sphinx-rtd-theme>=1.0,<2.1"]
+docs = ["toml~=0.10.2", "sphinx>=5,<9", "sphinx-rtd-theme>=1.0,<3.1"]
 test = ["pytest>=7.4,<9.0", "pytest-cov>=4,<6"]
 lint = ["pylint>=2.17,<3.4"]