diff --git a/pyproject.toml b/pyproject.toml
index 3fe13c3..5fbb662 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -63,7 +63,7 @@ optional = true
 
 [tool.poetry.group.docs.dependencies]
 sphinx = "^7.3.7"
-sphinx-rtd-theme = "^2.0.0"
+sphinx-rtd-theme = ">=2,<4"
 sphinx-copybutton = "^0.5.2"
 myst-parser = "^3.0.0"