diff --git a/pyproject.toml b/pyproject.toml
index 3b6d501..e395272 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -102,7 +102,7 @@ optional-dependencies.develop = [
   "poethepoet<0.28",
   "pyproject-fmt<2.3",
   "ruff<0.7",
-  "validate-pyproject<0.19",
+  "validate-pyproject<0.21",
 ]
 optional-dependencies.release = [
   "build<2",