diff --git a/setup.py b/setup.py
index 6482a6c8..20b80f17 100644
--- a/setup.py
+++ b/setup.py
@@ -39,7 +39,7 @@ def _parse_requirements(path, encoding="utf-8"):
     extras_require={
         "doc": [
             "sphinx>=4.5.0,<8.0.0",
-            "sphinx_rtd_theme>=1.0,<1.5",
+            "sphinx_rtd_theme>=1.0,<3.1",
             "sphinx-markdown-tables~=0.0.15",
             "sphinx-click>=3.1,<6.1",
             "sphinx_copybutton~=0.5.0",