diff --git a/pyproject.toml b/pyproject.toml
index 0e6926b..7a4e9ac 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -126,7 +126,7 @@ markers = [
 ]
 
 [tool.ruff]
-target-version = "py311"
+target-version = "py39"
 include = ["src/numpydantic/**/*.py", "pyproject.toml"]
 exclude = ["tests"]