diff --git a/pyproject.toml b/pyproject.toml
index b096b96..85d2f20 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,7 +23,7 @@ classifiers = [
 ]
 dependencies = [
     "syntax-diagrams>=1.0.0,<2.0",
-    "sphinx>=8.0,<9.0",
+    "sphinx>=8.0,<10.0",
     "PyYAML>=6.0,<7.0",
     "antlr4-python3-runtime>=4.13,<4.14",
 ]