diff --git a/pyproject.toml b/pyproject.toml
index 98f99b53..346e41ce 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -103,7 +103,7 @@ tests = [
 
 documentation = [
   "apache-burr[tests]",
-  "sphinx",
+  "sphinx<9",
   "sphinx-autobuild",
   "myst-nb",
   "furo",