diff --git a/pyproject.toml b/pyproject.toml
index f4b301b3e5..b8295ccd67 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,5 +1,6 @@
 [tool.ruff]
 line-length = 120
+target-version = "py39"
 
 [tool.ruff.lint]
 # https://docs.astral.sh/ruff/rules/