diff --git a/pyproject.toml b/pyproject.toml
index 27389bb..c01b676 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -95,7 +95,7 @@ optional-dependencies.develop = [
   "poethepoet<0.30",
   "pyproject-fmt<2.3",
   "ruff<0.7",
-  "validate-pyproject<0.20",
+  "validate-pyproject<0.21",
 ]
 optional-dependencies.doc = [
   "crate-docs-theme>=0.26.5",