diff --git a/pyproject.toml b/pyproject.toml
index 1976a2f..288d5df 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -90,7 +90,7 @@ optional-dependencies.develop = [
 optional-dependencies.docs = [
   "furo",
   "myst-parser[linkify]>=0.18,<5",
-  "sphinx<8",
+  "sphinx<10",
   "sphinx-autobuild==2025.8.25",   # Newer versions stopped "watching" appropriately?
   "sphinx-copybutton",
   "sphinx-design-elements<1",