diff --git a/mypy.ini b/mypy.ini
index 816e7f5..cd89e38 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -2,4 +2,5 @@
 disallow_untyped_defs = True
 check_untyped_defs = True
 warn_return_any = True
+python_version = 3.9
 mypy_path = $MYPY_CONFIG_FILE_DIR