diff --git a/pyproject.toml b/pyproject.toml
index 974ff9d..9559041 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -63,7 +63,7 @@ dev = [
     "ruff>=0.4.4,<0.5.0",
 ]
 docs = [
-    "sphinx>=5.0.0,<6.0.0",
+    "sphinx>=5.0.0,<9.0.0",
     "sphinx-rtd-theme>=1.0.0,<2.0.0",
     "sphinx-autodoc-typehints>=1.12.0,<2.0.0",
 ]
@@ -113,7 +113,7 @@ all = [
     "ruff>=0.4.4,<0.5.0",
 
     # docs
-    "sphinx>=5.0.0,<6.0.0",
+    "sphinx>=5.0.0,<9.0.0",
     "sphinx-rtd-theme>=1.0.0,<2.0.0",
     "sphinx-autodoc-typehints>=1.12.0,<2.0.0",