diff --git a/pyproject.toml b/pyproject.toml
index 6a417d30..dd9110cd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -93,7 +93,7 @@ optional-dependencies.dev = [
     "sphinx-paramlinks==0.6",
     "sphinx-pyproject==0.3.0",
     "sphinx-substitution-extensions==2025.3.3",
-    "sphinx-toolbox==3.8.3",
+    "sphinx-toolbox==3.9.0",
     "sphinxcontrib-httpdomain==1.8.1",
     "sphinxcontrib-spelling==8.0.1",
     "sybil==9.1.0",