diff --git a/pyproject.toml b/pyproject.toml
index 2a2a9d7d..3f79e053 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -342,6 +342,7 @@ markers = [
 [tool.ruff]
 src = ["ravenpy"]
 line-length = 150
+target-version = "py39"
 exclude = [
   ".eggs",
   ".git",