diff --git a/pyproject.toml b/pyproject.toml
index bb8dd6b..9c4afda 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -75,7 +75,7 @@ dependencies = [
 # 3: Optional dependencies.
 [project.optional-dependencies]
 docs = [
-	"sphinx <5.0, >=4.5.0",
+	"sphinx >=4.5.0, <9.0",
 	"sphinx-rtd-theme",
 ]