diff --git a/pyproject.toml b/pyproject.toml
index 1b13fa6..bd22632 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,7 +24,7 @@ python = ">=3.8"
 
 [tool.poetry.group.docs.dependencies]
 sphinx = ">=4.5,<7.2"
-sphinx_rtd_theme = ">=1.0,<1.4"
+sphinx_rtd_theme = ">=1.0,<2.1"
 
 [tool.poetry.group.dev.dependencies]
 coverage = {extras = ["toml"], version = ">=5.1,<8.0"}