diff --git a/pyproject.toml b/pyproject.toml
index 7b3f310617..546ee8f462 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -116,7 +116,7 @@ demo = [
   "ipython",
 ]
 doc = [
-  "sphinx>=6,<8",
+  "sphinx>=6,<9",
   "myst-parser==3.0.1",
   "Jinja2",
   "alabaster",