diff --git a/pyproject.toml b/pyproject.toml
index eebc770..9761ccd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -60,7 +60,7 @@ pre-commit = [
 ]
 
 docs = [
-    "sphinx>=7,<8",
+    "sphinx>=9,<10",
     "nbsphinx>=0.9,<1.0",
     "sphinx_rtd_theme>=3,<3.1",
     "sphinx_copybutton>=0.5,<1.0",