diff --git a/pyproject.toml b/pyproject.toml
index 66c47ac..82c41ba 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -84,7 +84,7 @@ dev = [
     # Transitive of mypy 2.1.x. Pin <0.5 because 0.5.0 only ships cp314
     # wheels (cp39-abi3 dropped), breaking CI on Python 3.12 + 3.13 runners.
     # Drop once upstream republishes broader wheels.
-    "ast-serialize<0.5",
+    "ast-serialize<0.6",
     "datamodel-code-generator>=0.26",
     "pyyaml>=6",
     "python-dotenv>=1",